flightgear/src/ATC/trafficcontrol.cxx

// trafficrecord.cxx - Implementation of AIModels ATC code.
//
// Written by Durk Talsma, started September 2006.
//
// Copyright (C) 2006 Durk Talsma.
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
//
// $Id$

#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif

#include <algorithm>

#include "trafficcontrol.hxx"
#include <AIModel/AIAircraft.hxx>
#include <AIModel/AIFlightPlan.hxx>
#include <AIModel/performancedata.hxx>
#include <AIModel/performancedb.hxx>
#include <Traffic/TrafficMgr.hxx>
#include <Airports/groundnetwork.hxx>
#include <Airports/dynamics.hxx>


using std::sort;

/***************************************************************************
 * ActiveRunway
 **************************************************************************/
time_t ActiveRunway::requestTimeSlot(time_t eta)
{
    time_t newEta;
    time_t separation = 90;
    bool found = false;
    if (estimatedArrivalTimes.size() == 0) {
        estimatedArrivalTimes.push_back(eta);
        return eta;
    } else {
        TimeVectorIterator i = estimatedArrivalTimes.begin();
        //cerr << "Checking eta slots " << eta << ": " << endl;
        for (i = estimatedArrivalTimes.begin();
             i != estimatedArrivalTimes.end(); i++) {
            //cerr << "Stored time : " << (*i) << endl;
        }
        i = estimatedArrivalTimes.begin();
        if ((eta + separation) < (*i)) {
            newEta = eta;
            found = true;
            //cerr << "Storing at beginning" << endl;
        }
        while ((i != estimatedArrivalTimes.end()) && (!found)) {
            TimeVectorIterator j = i + 1;
            if (j == estimatedArrivalTimes.end()) {
                if (((*i) + separation) < eta) {
                    //cerr << "Storing at end" << endl;
                    newEta = eta;
                } else {
                    newEta = (*i) + separation;
                    //cerr << "Storing at end + separation" << endl;
                }
            } else {
                if ((((*j) - (*i)) > (separation * 2))) {       // found a potential slot
                    // now check whether this slow is usable:
                    // 1) eta should fall between the two points
                    //    i.e. eta > i AND eta < j
                    //
                    //cerr << "Found potential slot after " << (*i) << endl;
                    if (eta > (*i) && (eta < (*j))) {
                        found = true;
                        if (eta < ((*i) + separation)) {
                            newEta = (*i) + separation;
                            //cerr << "Using  original" << (*i) << " + separation " << endl;
                        } else {
                            newEta = eta;
                            //cerr << "Using original after " << (*i) << endl;
                        }
                    } else if (eta < (*i)) {
                        found = true;
                        newEta = (*i) + separation;
                        //cerr << "Using delayed slot after " << (*i) << endl;
                    }
                    /*
                       if (((*j) - separation) < eta) {
                       found = true;
                       if (((*i) + separation) < eta) {
                       newEta = eta;
                       cerr << "Using original after " << (*i) << endl;
                       } else {
                       newEta = (*i) + separation;
                       cerr << "Using  " << (*i) << " + separation " << endl;
                       }
                       } */
                }
            }
            i++;
        }
    }
    //cerr << ". done. New ETA : " << newEta << endl;

    estimatedArrivalTimes.push_back(newEta);
    sort(estimatedArrivalTimes.begin(), estimatedArrivalTimes.end());
    // do some housekeeping : remove any timestamps that are past
    time_t now = time(NULL) + fgGetLong("/sim/time/warp");
    TimeVectorIterator i = estimatedArrivalTimes.begin();
    while (i != estimatedArrivalTimes.end()) {
        if ((*i) < now) {
            //cerr << "Deleting timestamp " << (*i) << " (now = " << now << "). " << endl;
            estimatedArrivalTimes.erase(i);
            i = estimatedArrivalTimes.begin();
        } else {
            i++;
        }
    }
    return newEta;
}

/***************************************************************************
 * FGTrafficRecord
 **************************************************************************/
FGTrafficRecord::FGTrafficRecord():
id(0), waitsForId(0),
currentPos(0),
leg(0),
frequencyId(0),
state(0),
allowTransmission(true),
latitude(0), longitude(0), heading(0), speed(0), altitude(0), radius(0)
{
}

void FGTrafficRecord::setPositionAndIntentions(int pos,
                                               FGAIFlightPlan * route)
{

    currentPos = pos;
    if (intentions.size()) {
        intVecIterator i = intentions.begin();
        if ((*i) != pos) {
            SG_LOG(SG_GENERAL, SG_ALERT,
                   "Error in FGTrafficRecord::setPositionAndIntentions");
            //cerr << "Pos : " << pos << " Curr " << *(intentions.begin())  << endl;
            for (intVecIterator i = intentions.begin();
                 i != intentions.end(); i++) {
                //cerr << (*i) << " ";
            }
            //cerr << endl;
        }
        intentions.erase(i);
    } else {
        //FGAIFlightPlan::waypoint* const wpt= route->getCurrentWaypoint();
        int size = route->getNrOfWayPoints();
        //cerr << "Setting pos" << pos << " ";
        //cerr << "setting intentions ";
        for (int i = 0; i < size; i++) {
            int val = route->getRouteIndex(i);
            //cerr << val<< " ";
            if ((val) && (val != pos)) {
                intentions.push_back(val);
                //cerr << "[set] ";
            }
        }
        //cerr << endl;
        //while (route->next(&legNr, &routeNr)) {
        //intentions.push_back(routeNr);
        //}
        //route->rewind(currentPos);
    }
    //exit(1);
}

bool FGTrafficRecord::checkPositionAndIntentions(FGTrafficRecord & other)
{
    bool result = false;
    //cerr << "Start check 1" << endl;
    if (currentPos == other.currentPos) {
        //cerr << callsign << ": Check Position and intentions: we are on the same taxiway" << other.callsign << "Index = " << currentPos << endl;
        result = true;
    }
    //  else if (other.intentions.size()) 
    //     {
    //       cerr << "Start check 2" << endl;
    //       intVecIterator i = other.intentions.begin(); 
    //       while (!((i == other.intentions.end()) || ((*i) == currentPos)))
    //     i++;
    //       if (i != other.intentions.end()) {
    //     cerr << "Check Position and intentions: current matches other.intentions" << endl;
    //     result = true;
    //       }
    else if (intentions.size()) {
        //cerr << "Start check 3" << endl;
        intVecIterator i = intentions.begin();
        //while (!((i == intentions.end()) || ((*i) == other.currentPos)))
        while (i != intentions.end()) {
            if ((*i) == other.currentPos) {
                break;
            }
            i++;
        }
        if (i != intentions.end()) {
            //cerr << callsign << ": Check Position and intentions: .other.current matches" << other.callsign << "Index = " << (*i) << endl;
            result = true;
        }
    }
    //cerr << "Done !!" << endl;
    return result;
}

void FGTrafficRecord::setPositionAndHeading(double lat, double lon,
                                            double hdg, double spd,
                                            double alt)
{
    latitude = lat;
    longitude = lon;
    heading = hdg;
    speed = spd;
    altitude = alt;
}

int FGTrafficRecord::crosses(FGGroundNetwork * net,
                             FGTrafficRecord & other)
{
    if (checkPositionAndIntentions(other)
        || (other.checkPositionAndIntentions(*this)))
        return -1;
    intVecIterator i, j;
    int currentTargetNode = 0, otherTargetNode = 0;
    if (currentPos > 0)
        currentTargetNode = net->findSegment(currentPos)->getEnd()->getIndex(); // OKAY,... 
    if (other.currentPos > 0)
        otherTargetNode = net->findSegment(other.currentPos)->getEnd()->getIndex();     // OKAY,...
    if ((currentTargetNode == otherTargetNode) && currentTargetNode > 0)
        return currentTargetNode;
    if (intentions.size()) {
        for (i = intentions.begin(); i != intentions.end(); i++) {
            if ((*i) > 0) {
                if ((currentTargetNode ==
                     net->findSegment(*i)->getEnd()->getIndex())) {
                    //cerr << "Current crosses at " << currentTargetNode <<endl;
                    return currentTargetNode;
                }
            }
        }
    }
    if (other.intentions.size()) {
        for (i = other.intentions.begin(); i != other.intentions.end();
             i++) {
            if ((*i) > 0) {
                if (otherTargetNode ==
                    net->findSegment(*i)->getEnd()->getIndex()) {
                    //cerr << "Other crosses at " << currentTargetNode <<endl;
                    return otherTargetNode;
                }
            }
        }
    }
    if (intentions.size() && other.intentions.size()) {
        for (i = intentions.begin(); i != intentions.end(); i++) {
            for (j = other.intentions.begin(); j != other.intentions.end();
                 j++) {
                //cerr << "finding segment " << *i << " and " << *j << endl;
                if (((*i) > 0) && ((*j) > 0)) {
                    currentTargetNode =
                        net->findSegment(*i)->getEnd()->getIndex();
                    otherTargetNode =
                        net->findSegment(*j)->getEnd()->getIndex();
                    if (currentTargetNode == otherTargetNode) {
                        //cerr << "Routes will cross at " << currentTargetNode << endl;
                        return currentTargetNode;
                    }
                }
            }
        }
    }
    return -1;
}

bool FGTrafficRecord::onRoute(FGGroundNetwork * net,
                              FGTrafficRecord & other)
{
    int node = -1, othernode = -1;
    if (currentPos > 0)
        node = net->findSegment(currentPos)->getEnd()->getIndex();
    if (other.currentPos > 0)
        othernode =
            net->findSegment(other.currentPos)->getEnd()->getIndex();
    if ((node == othernode) && (node != -1))
        return true;
    if (other.intentions.size()) {
        for (intVecIterator i = other.intentions.begin();
             i != other.intentions.end(); i++) {
            if (*i > 0) {
                othernode = net->findSegment(*i)->getEnd()->getIndex();
                if ((node == othernode) && (node > -1))
                    return true;
            }
        }
    }
    //if (other.currentPos > 0)
    //  othernode = net->findSegment(other.currentPos)->getEnd()->getIndex();
    //if (intentions.size())
    //  {
    //    for (intVecIterator i = intentions.begin(); i != intentions.end(); i++)
    //    {
    //      if (*i > 0) 
    //        {
    //          node = net->findSegment(*i)->getEnd()->getIndex();
    //          if ((node == othernode) && (node > -1))
    //            return true;
    //        }
    //    }
    //  }
    return false;
}


bool FGTrafficRecord::isOpposing(FGGroundNetwork * net,
                                 FGTrafficRecord & other, int node)
{
    // Check if current segment is the reverse segment for the other aircraft
    FGTaxiSegment *opp;
    //cerr << "Current segment " << currentPos << endl;
    if ((currentPos > 0) && (other.currentPos > 0)) {
        opp = net->findSegment(currentPos)->opposite();
        if (opp) {
            if (opp->getIndex() == other.currentPos)
                return true;
        }

        for (intVecIterator i = intentions.begin(); i != intentions.end();
             i++) {
            if ((opp = net->findSegment(other.currentPos)->opposite())) {
                if ((*i) > 0)
                    if (opp->getIndex() ==
                        net->findSegment(*i)->getIndex()) {
                        if (net->findSegment(*i)->getStart()->getIndex() ==
                            node) {
                            {
                                //cerr << "Found the node " << node << endl;
                                return true;
                            }
                        }
                    }
            }
            if (other.intentions.size()) {
                for (intVecIterator j = other.intentions.begin();
                     j != other.intentions.end(); j++) {
                    // cerr << "Current segment 1 " << (*i) << endl;
                    if ((*i) > 0) {
                        if ((opp = net->findSegment(*i)->opposite())) {
                            if (opp->getIndex() ==
                                net->findSegment(*j)->getIndex()) {
                                //cerr << "Nodes " << net->findSegment(*i)->getIndex()
                                //   << " and  " << net->findSegment(*j)->getIndex()
                                //   << " are opposites " << endl;
                                if (net->findSegment(*i)->getStart()->
                                    getIndex() == node) {
                                    {
                                        //cerr << "Found the node " << node << endl;
                                        return true;
                                    }
                                }
                            }
                        }
                    }
                }
            }
        }
    }
    return false;
}

void FGTrafficRecord::setSpeedAdjustment(double spd)
{
    instruction.setChangeSpeed(true);
    instruction.setSpeed(spd);
}

void FGTrafficRecord::setHeadingAdjustment(double heading)
{
    instruction.setChangeHeading(true);
    instruction.setHeading(heading);
}

bool FGTrafficRecord::pushBackAllowed()
{
    double course, az2, dist;
    SGGeod curr(SGGeod::fromDegM(getLongitude(),
                                 getLatitude(), getAltitude()));

    double userLatitude = fgGetDouble("/position/latitude-deg");
    double userLongitude = fgGetDouble("/position/longitude-deg");
    SGGeod user(SGGeod::fromDeg(userLongitude, userLatitude));
    SGGeodesy::inverse(curr, user, course, az2, dist);
    //cerr << "Distance to user : " << dist << endl;
    return (dist > 250);

}



/***************************************************************************
 * FGATCInstruction
 *
 **************************************************************************/
FGATCInstruction::FGATCInstruction()
{
    holdPattern = false;
    holdPosition = false;
    changeSpeed = false;
    changeHeading = false;
    changeAltitude = false;
    resolveCircularWait = false;

    speed = 0;
    heading = 0;
    alt = 0;
}


bool FGATCInstruction::hasInstruction()
{
    return (holdPattern || holdPosition || changeSpeed || changeHeading
            || changeAltitude || resolveCircularWait);
}

/***************************************************************************
 * FGATCController
 *
 **************************************************************************/




FGATCController::FGATCController()
{
    dt_count = 0;
    available = true;
    lastTransmission = 0;
}

string FGATCController::getGateName(FGAIAircraft * ref)
{
    return ref->atGate();
}

void FGATCController::transmit(FGTrafficRecord * rec, AtcMsgId msgId,
                               AtcMsgDir msgDir)
{
    string sender, receiver;
    int stationFreq = 0;
    int taxiFreq = 0;
    int freqId = 0;
    string atisInformation;
    string text;
    string taxiFreqStr;
    double heading = 0;
    string activeRunway;
    string fltType;
    string rwyClass;
    string SID;
    string transponderCode;
    FGAIFlightPlan *fp;
    string fltRules;

    //double commFreqD;
    sender = rec->getAircraft()->getTrafficRef()->getCallSign();
    //cerr << "transmitting for: " << sender << "Leg = " << rec->getLeg() << endl;
    switch (rec->getLeg()) {
    case 2:
    case 3:
        freqId = rec->getNextFrequency();
        stationFreq =
            rec->getAircraft()->getTrafficRef()->getDepartureAirport()->
            getDynamics()->getGroundFrequency(rec->getLeg() + freqId);
        taxiFreq =
            rec->getAircraft()->getTrafficRef()->getDepartureAirport()->
            getDynamics()->getGroundFrequency(3);
        receiver =
            rec->getAircraft()->getTrafficRef()->getDepartureAirport()->
            getName() + "-Ground";
        atisInformation =
            rec->getAircraft()->getTrafficRef()->getDepartureAirport()->
            getDynamics()->getAtisInformation();
        break;
    case 4:
        receiver =
            rec->getAircraft()->getTrafficRef()->getDepartureAirport()->
            getName() + "-Tower";
        break;
    }
    // Swap sender and receiver value in case of a ground to air transmission
    if (msgDir == ATC_GROUND_TO_AIR) {
        string tmp = sender;
        sender = receiver;
        receiver = tmp;
    }
    switch (msgId) {
    case MSG_ANNOUNCE_ENGINE_START:
        text = sender + ". Ready to Start up";
        break;
    case MSG_REQUEST_ENGINE_START:
        text =
            receiver + ", This is " + sender + ". Position " +
            getGateName(rec->getAircraft()) + ". Information " +
            atisInformation + ". " +
            rec->getAircraft()->getTrafficRef()->getFlightRules() +
            " to " +
            rec->getAircraft()->getTrafficRef()->getArrivalAirport()->
            getName() + ". Request start-up";
        break;
        // Acknowledge engine startup permission
        // Assign departure runway
        // Assign SID, if necessery (TODO)
    case MSG_PERMIT_ENGINE_START:
        taxiFreqStr = formatATCFrequency3_2(taxiFreq);

        heading = rec->getAircraft()->getTrafficRef()->getCourse();
        fltType = rec->getAircraft()->getTrafficRef()->getFlightType();
        rwyClass =
            rec->getAircraft()->GetFlightPlan()->
            getRunwayClassFromTrafficType(fltType);

        rec->getAircraft()->getTrafficRef()->getDepartureAirport()->
            getDynamics()->getActiveRunway(rwyClass, 1, activeRunway,
                                           heading);
        rec->getAircraft()->GetFlightPlan()->setRunway(activeRunway);
        fp = rec->getAircraft()->getTrafficRef()->getDepartureAirport()->
            getDynamics()->getSID(activeRunway, heading);
        rec->getAircraft()->GetFlightPlan()->setSID(fp);
        if (fp) {
            SID = fp->getName() + " departure";
        } else {
            SID = "fly runway heading ";
        }
        //snprintf(buffer, 7, "%3.2f", heading);
        fltRules = rec->getAircraft()->getTrafficRef()->getFlightRules();
        transponderCode = genTransponderCode(fltRules);
        rec->getAircraft()->SetTransponderCode(transponderCode);
        text =
            receiver + ". Start-up approved. " + atisInformation +
            " correct, runway " + activeRunway + ", " + SID + ", squawk " +
            transponderCode + ". " +
            "For push-back and taxi clearance call " + taxiFreqStr + ". " +
            sender + " control.";
        break;
    case MSG_DENY_ENGINE_START:
        text = receiver + ". Standby";
        break;
    case MSG_ACKNOWLEDGE_ENGINE_START:
        fp = rec->getAircraft()->GetFlightPlan()->getSID();
        if (fp) {
            SID =
                rec->getAircraft()->GetFlightPlan()->getSID()->getName() +
                " departure";
        } else {
            SID = "fly runway heading ";
        }
        taxiFreqStr = formatATCFrequency3_2(taxiFreq);
        activeRunway = rec->getAircraft()->GetFlightPlan()->getRunway();
        transponderCode = rec->getAircraft()->GetTransponderCode();
        text =
            receiver + ". Start-up approved. " + atisInformation +
            " correct, runway " + activeRunway + ", " + SID + ", squawk " +
            transponderCode + ". " +
            "For push-back and taxi clearance call " + taxiFreqStr + ". " +
            sender;
        break;
    case MSG_ACKNOWLEDGE_SWITCH_GROUND_FREQUENCY:
        taxiFreqStr = formatATCFrequency3_2(taxiFreq);
        text = receiver + ". Switching to " + taxiFreqStr + ". " + sender;
        break;
    case MSG_INITIATE_CONTACT:
        text = receiver + ". With you. " + sender;
        break;
    case MSG_ACKNOWLEDGE_INITIATE_CONTACT:
        text = receiver + ". Roger. " + sender;
        break;
    case MSG_REQUEST_PUSHBACK_CLEARANCE:
        text = receiver + ". Request push-back. " + sender;
        break;
    case MSG_PERMIT_PUSHBACK_CLEARANCE:
        text = receiver + ". Push-back approved. " + sender;
        break;
    case MSG_HOLD_PUSHBACK_CLEARANCE:
        text = receiver + ". Standby. " + sender;
        break;
    case MSG_REQUEST_TAXI_CLEARANCE:
        text = receiver + ". Ready to Taxi. " + sender;
        break;
    case MSG_ISSUE_TAXI_CLEARANCE:
        text = receiver + ". Cleared to taxi. " + sender;
        break;
    case MSG_ACKNOWLEDGE_TAXI_CLEARANCE:
        text = receiver + ". Cleared to taxi. " + sender;
        break;
    case MSG_HOLD_POSITION:
        text = receiver + ". Hold Position. " + sender;
        break;
    case MSG_ACKNOWLEDGE_HOLD_POSITION:
        text = receiver + ". Holding Position. " + sender;
        break;
    case MSG_RESUME_TAXI:
        text = receiver + ". Resume Taxiing. " + sender;
        break;
    case MSG_ACKNOWLEDGE_RESUME_TAXI:
        text = receiver + ". Continuing Taxi. " + sender;
        break;
    default:
        text = text + sender + ". Transmitting unknown Message";
        break;
    }
    double onBoardRadioFreq0 =
        fgGetDouble("/instrumentation/comm[0]/frequencies/selected-mhz");
    double onBoardRadioFreq1 =
        fgGetDouble("/instrumentation/comm[1]/frequencies/selected-mhz");
    int onBoardRadioFreqI0 = (int) floor(onBoardRadioFreq0 * 100 + 0.5);
    int onBoardRadioFreqI1 = (int) floor(onBoardRadioFreq1 * 100 + 0.5);
    //cerr << "Using " << onBoardRadioFreq0 << ", " << onBoardRadioFreq1 << " and " << stationFreq << " for " << text << endl;

    // Display ATC message only when one of the radios is tuned
    // the relevant frequency.
    // Note that distance attenuation is currently not yet implemented
    if ((onBoardRadioFreqI0 == stationFreq)
        || (onBoardRadioFreqI1 == stationFreq)) {
        if (rec->allowTransmissions()) {
            fgSetString("/sim/messages/atc", text.c_str());
        }
    }
}

string FGATCController::formatATCFrequency3_2(int freq)
{
    char buffer[7];
    snprintf(buffer, 7, "%3.2f", ((float) freq / 100.0));
    return string(buffer);
}

// TODO: Set transponder codes according to real-world routes.
// The current version just returns a random string of four octal numbers. 
string FGATCController::genTransponderCode(string fltRules)
{
    if (fltRules == "VFR") {
        return string("1200");
    } else {
        char buffer[5];
        snprintf(buffer, 5, "%d%d%d%d", rand() % 8, rand() % 8, rand() % 8,
                 rand() % 8);
        return string(buffer);
    }
}

/***************************************************************************
 * class FGTowerController
 *
 **************************************************************************/
FGTowerController::FGTowerController():
FGATCController()
{
}

// 
void FGTowerController::announcePosition(int id,
                                         FGAIFlightPlan * intendedRoute,
                                         int currentPosition, double lat,
                                         double lon, double heading,
                                         double speed, double alt,
                                         double radius, int leg,
                                         FGAIAircraft * ref)
{
    TrafficVectorIterator i = activeTraffic.begin();
    // Search whether the current id alread has an entry
    // This might be faster using a map instead of a vector, but let's start by taking a safe route
    if (activeTraffic.size()) {
        //while ((i->getId() != id) && i != activeTraffic.end()) {
        while (i != activeTraffic.end()) {
            if (i->getId() == id) {
                break;
            }
            i++;
        }
    }
    // Add a new TrafficRecord if no one exsists for this aircraft.
    if (i == activeTraffic.end() || (activeTraffic.size() == 0)) {
        FGTrafficRecord rec;
        rec.setId(id);

        rec.setPositionAndHeading(lat, lon, heading, speed, alt);
        rec.setRunway(intendedRoute->getRunway());
        rec.setLeg(leg);
        //rec.setCallSign(callsign);
        rec.setAircraft(ref);
        activeTraffic.push_back(rec);
    } else {
        i->setPositionAndHeading(lat, lon, heading, speed, alt);
    }
}

void FGTowerController::update(int id, double lat, double lon,
                               double heading, double speed, double alt,
                               double dt)
{
    TrafficVectorIterator i = activeTraffic.begin();
    // Search whether the current id has an entry
    // This might be faster using a map instead of a vector, but let's start by taking a safe route
    TrafficVectorIterator current, closest;
    if (activeTraffic.size()) {
        //while ((i->getId() != id) && i != activeTraffic.end()) {
        while (i != activeTraffic.end()) {
            if (i->getId() == id) {
                break;
            }
            i++;
        }
    }
//    // update position of the current aircraft
    if (i == activeTraffic.end() || (activeTraffic.size() == 0)) {
        SG_LOG(SG_GENERAL, SG_ALERT,
               "AI error: updating aircraft without traffic record");
    } else {
        i->setPositionAndHeading(lat, lon, heading, speed, alt);
        current = i;
    }
    setDt(getDt() + dt);

//    // see if we already have a clearance record for the currently active runway
    ActiveRunwayVecIterator rwy = activeRunways.begin();
    // again, a map might be more efficient here
    if (activeRunways.size()) {
        //while ((rwy->getRunwayName() != current->getRunway()) && (rwy != activeRunways.end())) {
        while (rwy != activeRunways.end()) {
            if (rwy->getRunwayName() == current->getRunway()) {
                break;
            }
            rwy++;
        }
    }
    if (rwy == activeRunways.end()) {
        ActiveRunway aRwy(current->getRunway(), id);
        activeRunways.push_back(aRwy);  // Since there are no clearance records for this runway yet
        current->setHoldPosition(false);        // Clear the current aircraft to continue
    } else {
        // Okay, we have a clearance record for this runway, so check
        // whether the clearence ID matches that of the current aircraft
        if (id == rwy->getCleared()) {
            current->setHoldPosition(false);
        } else {
            current->setHoldPosition(true);
        }
    }
}


void FGTowerController::signOff(int id)
{
    TrafficVectorIterator i = activeTraffic.begin();
    // Search search if the current id alread has an entry
    // This might be faster using a map instead of a vector, but let's start by taking a safe route
    if (activeTraffic.size()) {
        //while ((i->getId() != id) && i != activeTraffic.end()) {
        while (i != activeTraffic.end()) {
            if (i->getId() == id) {
                break;
            }
            i++;
        }
    }
    // If this aircraft has left the runway, we can clear the departure record for this runway
    ActiveRunwayVecIterator rwy = activeRunways.begin();
    if (activeRunways.size()) {
        //while ((rwy->getRunwayName() != i->getRunway()) && (rwy != activeRunways.end())) {
        while (rwy != activeRunways.end()) {
            if (rwy->getRunwayName() == i->getRunway()) {
                break;
            }
            rwy++;
        }
        if (rwy != activeRunways.end()) {
            rwy = activeRunways.erase(rwy);
        } else {
            SG_LOG(SG_GENERAL, SG_ALERT,
                   "AI error: Attempting to erase non-existing runway clearance record in FGTowerController::signoff");
        }
    }
    if (i == activeTraffic.end() || (activeTraffic.size() == 0)) {
        SG_LOG(SG_GENERAL, SG_ALERT,
               "AI error: Aircraft without traffic record is signing off from tower");
    } else {
        i = activeTraffic.erase(i);
    }
}

// NOTE:
// IF WE MAKE TRAFFICRECORD A MEMBER OF THE BASE CLASS
// THE FOLLOWING THREE FUNCTIONS: SIGNOFF, HAS INSTRUCTION AND GETINSTRUCTION CAN 
// BECOME DEVIRTUALIZED AND BE A MEMBER OF THE BASE ATCCONTROLLER CLASS
// WHICH WOULD SIMPLIFY CODE MAINTENANCE.
// Note that this function is probably obsolete
bool FGTowerController::hasInstruction(int id)
{
    TrafficVectorIterator i = activeTraffic.begin();
    // Search search if the current id has an entry
    // This might be faster using a map instead of a vector, but let's start by taking a safe route
    if (activeTraffic.size()) {
        //while ((i->getId() != id) && i != activeTraffic.end()) {
        while (i != activeTraffic.end()) {
            if (i->getId() == id) {
                break;
            }
            i++;
        }
    }
    if (i == activeTraffic.end() || (activeTraffic.size() == 0)) {
        SG_LOG(SG_GENERAL, SG_ALERT,
               "AI error: checking ATC instruction for aircraft without traffic record");
    } else {
        return i->hasInstruction();
    }
    return false;
}


FGATCInstruction FGTowerController::getInstruction(int id)
{
    TrafficVectorIterator i = activeTraffic.begin();
    // Search search if the current id has an entry
    // This might be faster using a map instead of a vector, but let's start by taking a safe route
    if (activeTraffic.size()) {
        //while ((i->getId() != id) && i != activeTraffic.end()) {
        while (i != activeTraffic.end()) {
            if (i->getId() == id) {
                break;
            }
            i++;
        }
    }
    if (i == activeTraffic.end() || (activeTraffic.size() == 0)) {
        SG_LOG(SG_GENERAL, SG_ALERT,
               "AI error: requesting ATC instruction for aircraft without traffic record");
    } else {
        return i->getInstruction();
    }
    return FGATCInstruction();
}

/***************************************************************************
 * class FGStartupController
 *
 **************************************************************************/
FGStartupController::FGStartupController():
FGATCController()
{
}

void FGStartupController::announcePosition(int id,
                                           FGAIFlightPlan * intendedRoute,
                                           int currentPosition, double lat,
                                           double lon, double heading,
                                           double speed, double alt,
                                           double radius, int leg,
                                           FGAIAircraft * ref)
{
    TrafficVectorIterator i = activeTraffic.begin();
    // Search whether the current id alread has an entry
    // This might be faster using a map instead of a vector, but let's start by taking a safe route
    if (activeTraffic.size()) {
        //while ((i->getId() != id) && i != activeTraffic.end()) {
        while (i != activeTraffic.end()) {
            if (i->getId() == id) {
                break;
            }
            i++;
        }
    }
    // Add a new TrafficRecord if no one exsists for this aircraft.
    if (i == activeTraffic.end() || (activeTraffic.size() == 0)) {
        FGTrafficRecord rec;
        rec.setId(id);

        rec.setPositionAndHeading(lat, lon, heading, speed, alt);
        rec.setRunway(intendedRoute->getRunway());
        rec.setLeg(leg);
        //rec.setCallSign(callsign);
        rec.setAircraft(ref);
        rec.setHoldPosition(true);
        activeTraffic.push_back(rec);
    } else {
        i->setPositionAndHeading(lat, lon, heading, speed, alt);

    }
}

// NOTE:
// IF WE MAKE TRAFFICRECORD A MEMBER OF THE BASE CLASS
// THE FOLLOWING THREE FUNCTIONS: SIGNOFF, HAS INSTRUCTION AND GETINSTRUCTION CAN 
// BECOME DEVIRTUALIZED AND BE A MEMBER OF THE BASE ATCCONTROLLER CLASS
// WHICH WOULD SIMPLIFY CODE MAINTENANCE.
// Note that this function is probably obsolete
bool FGStartupController::hasInstruction(int id)
{
    TrafficVectorIterator i = activeTraffic.begin();
    // Search search if the current id has an entry
    // This might be faster using a map instead of a vector, but let's start by taking a safe route
    if (activeTraffic.size()) {
        //while ((i->getId() != id) && i != activeTraffic.end()) {
        while (i != activeTraffic.end()) {
            if (i->getId() == id) {
                break;
            }
            i++;
        }
    }
    if (i == activeTraffic.end() || (activeTraffic.size() == 0)) {
        SG_LOG(SG_GENERAL, SG_ALERT,
               "AI error: checking ATC instruction for aircraft without traffic record");
    } else {
        return i->hasInstruction();
    }
    return false;
}


FGATCInstruction FGStartupController::getInstruction(int id)
{
    TrafficVectorIterator i = activeTraffic.begin();
    // Search search if the current id has an entry
    // This might be faster using a map instead of a vector, but let's start by taking a safe route
    if (activeTraffic.size()) {
        //while ((i->getId() != id) && i != activeTraffic.end()) {
        while (i != activeTraffic.end()) {
            if (i->getId() == id) {
                break;
            }
            i++;
        }
    }
    if (i == activeTraffic.end() || (activeTraffic.size() == 0)) {
        SG_LOG(SG_GENERAL, SG_ALERT,
               "AI error: requesting ATC instruction for aircraft without traffic record");
    } else {
        return i->getInstruction();
    }
    return FGATCInstruction();
}

void FGStartupController::signOff(int id)
{
    TrafficVectorIterator i = activeTraffic.begin();
    // Search search if the current id alread has an entry
    // This might be faster using a map instead of a vector, but let's start by taking a safe route
    if (activeTraffic.size()) {
        //while ((i->getId() != id) && i != activeTraffic.end()) {
        while (i != activeTraffic.end()) {
            if (i->getId() == id) {
                break;
            }
            i++;
        }
    }
    if (i == activeTraffic.end() || (activeTraffic.size() == 0)) {
        SG_LOG(SG_GENERAL, SG_ALERT,
               "AI error: Aircraft without traffic record is signing off from tower");
    } else {
        i = activeTraffic.erase(i);
    }
}

void FGStartupController::update(int id, double lat, double lon,
                                 double heading, double speed, double alt,
                                 double dt)
{
    TrafficVectorIterator i = activeTraffic.begin();
    // Search search if the current id has an entry
    // This might be faster using a map instead of a vector, but let's start by taking a safe route
    TrafficVectorIterator current, closest;
    if (activeTraffic.size()) {
        //while ((i->getId() != id) && i != activeTraffic.end()) {
        while (i != activeTraffic.end()) {
            if (i->getId() == id) {
                break;
            }
            i++;
        }
    }
//    // update position of the current aircraft
    if (i == activeTraffic.end() || (activeTraffic.size() == 0)) {
        SG_LOG(SG_GENERAL, SG_ALERT,
               "AI error: updating aircraft without traffic record");
    } else {
        i->setPositionAndHeading(lat, lon, heading, speed, alt);
        current = i;
    }
    setDt(getDt() + dt);

    int state = i->getState();
    time_t startTime =
        i->getAircraft()->getTrafficRef()->getDepartureTime();
    time_t now = time(NULL) + fgGetLong("/sim/time/warp");
    //cerr << i->getAircraft()->getTrafficRef()->getCallSign() 
    //     << " is scheduled to depart in " << startTime-now << " seconds. Available = " << available
    //     << " at parking " << getGateName(i->getAircraft()) << endl;

    if ((now - lastTransmission) > 3 + (rand() % 15)) {
        available = true;
    }

    if ((state == 0) && available) {
        if (now > startTime) {
            //cerr << "Transmitting startup msg" << endl;
            transmit(&(*i), MSG_ANNOUNCE_ENGINE_START, ATC_AIR_TO_GROUND);
            i->updateState();
            lastTransmission = now;
            available = false;
        }
    }
    if ((state == 1) && available) {
        if (now > startTime + 60) {
            transmit(&(*i), MSG_REQUEST_ENGINE_START, ATC_AIR_TO_GROUND);
            i->updateState();
            lastTransmission = now;
            available = false;
        }
    }
    if ((state == 2) && available) {
        if (now > startTime + 80) {
            transmit(&(*i), MSG_PERMIT_ENGINE_START, ATC_GROUND_TO_AIR);
            i->updateState();
            lastTransmission = now;
            available = false;
        }
    }
    if ((state == 3) && available) {
        if (now > startTime + 100) {
            transmit(&(*i), MSG_ACKNOWLEDGE_ENGINE_START,
                     ATC_AIR_TO_GROUND);
            i->updateState();
            lastTransmission = now;
            available = false;
        }
    }
    // Note: The next four stages are only necessesary when Startup control is
    //  on a different frequency, compared to ground control
    if ((state == 4) && available) {
        if (now > startTime + 130) {
            transmit(&(*i), MSG_ACKNOWLEDGE_SWITCH_GROUND_FREQUENCY,
                     ATC_AIR_TO_GROUND);
            i->updateState();
            i->nextFrequency();
            lastTransmission = now;
            available = false;
        }
    }
    if ((state == 5) && available) {
        if (now > startTime + 140) {
            transmit(&(*i), MSG_INITIATE_CONTACT, ATC_AIR_TO_GROUND);
            i->updateState();
            lastTransmission = now;
            available = false;
        }
    }
    if ((state == 6) && available) {
        if (now > startTime + 150) {
            transmit(&(*i), MSG_ACKNOWLEDGE_INITIATE_CONTACT,
                     ATC_GROUND_TO_AIR);
            i->updateState();
            lastTransmission = now;
            available = false;
        }
    }

    // TODO: Switch to APRON control and request pushback Clearance.
    // Get Push back clearance
    if ((state == 7) && available) {
        if (now > startTime + 180) {
            transmit(&(*i), MSG_REQUEST_PUSHBACK_CLEARANCE,
                     ATC_AIR_TO_GROUND);
            i->updateState();
            lastTransmission = now;
            available = false;
        }
    }
    if ((state == 8) && available) {
        if (now > startTime + 200) {
            if (i->pushBackAllowed()) {
                i->allowRepeatedTransmissions();
                transmit(&(*i), MSG_PERMIT_PUSHBACK_CLEARANCE,
                         ATC_GROUND_TO_AIR);
                i->updateState();
            } else {
                transmit(&(*i), MSG_HOLD_PUSHBACK_CLEARANCE,
                         ATC_GROUND_TO_AIR);
                i->suppressRepeatedTransmissions();
            }
            lastTransmission = now;
            available = false;
        }
    }
    if ((state == 9) && available) {
        i->setHoldPosition(false);
    }
}


/***************************************************************************
 * class FGApproachController
 *
 **************************************************************************/
FGApproachController::FGApproachController():
FGATCController()
{
}

// 
void FGApproachController::announcePosition(int id,
                                            FGAIFlightPlan * intendedRoute,
                                            int currentPosition,
                                            double lat, double lon,
                                            double heading, double speed,
                                            double alt, double radius,
                                            int leg, FGAIAircraft * ref)
{
    TrafficVectorIterator i = activeTraffic.begin();
    // Search whether the current id alread has an entry
    // This might be faster using a map instead of a vector, but let's start by taking a safe route
    if (activeTraffic.size()) {
        //while ((i->getId() != id) && i != activeTraffic.end()) {
        while (i != activeTraffic.end()) {
            if (i->getId() == id) {
                break;
            }
            i++;
        }
    }
    // Add a new TrafficRecord if no one exsists for this aircraft.
    if (i == activeTraffic.end() || (activeTraffic.size() == 0)) {
        FGTrafficRecord rec;
        rec.setId(id);

        rec.setPositionAndHeading(lat, lon, heading, speed, alt);
        rec.setRunway(intendedRoute->getRunway());
        rec.setLeg(leg);
        //rec.setCallSign(callsign);
        rec.setAircraft(ref);
        activeTraffic.push_back(rec);
    } else {
        i->setPositionAndHeading(lat, lon, heading, speed, alt);
    }
}

void FGApproachController::update(int id, double lat, double lon,
                                  double heading, double speed, double alt,
                                  double dt)
{
    TrafficVectorIterator i = activeTraffic.begin();
    // Search search if the current id has an entry
    // This might be faster using a map instead of a vector, but let's start by taking a safe route
    TrafficVectorIterator current, closest;
    if (activeTraffic.size()) {
        //while ((i->getId() != id) && i != activeTraffic.end()) {
        while (i != activeTraffic.end()) {
            if (i->getId() == id) {
                break;
            }
            i++;
        }
    }
//    // update position of the current aircraft
    if (i == activeTraffic.end() || (activeTraffic.size() == 0)) {
        SG_LOG(SG_GENERAL, SG_ALERT,
               "AI error: updating aircraft without traffic record");
    } else {
        i->setPositionAndHeading(lat, lon, heading, speed, alt);
        current = i;
        //cerr << "ApproachController: checking for speed" << endl;
        time_t time_diff =
            current->getAircraft()->
            checkForArrivalTime(string("final001"));
        if (time_diff > 15) {
            current->setSpeedAdjustment(current->getAircraft()->
                                        getPerformance()->vDescent() *
                                        1.35);
        } else if (time_diff > 5) {
            current->setSpeedAdjustment(current->getAircraft()->
                                        getPerformance()->vDescent() *
                                        1.2);
        } else if (time_diff < -15) {
            current->setSpeedAdjustment(current->getAircraft()->
                                        getPerformance()->vDescent() *
                                        0.65);
        } else if (time_diff < -5) {
            current->setSpeedAdjustment(current->getAircraft()->
                                        getPerformance()->vDescent() *
                                        0.8);
        } else {
            current->clearSpeedAdjustment();
        }
        //current->setSpeedAdjustment(current->getAircraft()->getPerformance()->vDescent() + time_diff);
    }
    setDt(getDt() + dt);
}

void FGApproachController::signOff(int id)
{
    TrafficVectorIterator i = activeTraffic.begin();
    // Search search if the current id alread has an entry
    // This might be faster using a map instead of a vector, but let's start by taking a safe route
    if (activeTraffic.size()) {
        //while ((i->getId() != id) && i != activeTraffic.end()) {
        while (i != activeTraffic.end()) {
            if (i->getId() == id) {
                break;
            }
            i++;
        }
    }
    if (i == activeTraffic.end() || (activeTraffic.size() == 0)) {
        SG_LOG(SG_GENERAL, SG_ALERT,
               "AI error: Aircraft without traffic record is signing off from approach");
    } else {
        i = activeTraffic.erase(i);
    }
}




bool FGApproachController::hasInstruction(int id)
{
    TrafficVectorIterator i = activeTraffic.begin();
    // Search search if the current id has an entry
    // This might be faster using a map instead of a vector, but let's start by taking a safe route
    if (activeTraffic.size()) {
        //while ((i->getId() != id) && i != activeTraffic.end()) {
        while (i != activeTraffic.end()) {
            if (i->getId() == id) {
                break;
            }
            i++;
        }
    }
    if (i == activeTraffic.end() || (activeTraffic.size() == 0)) {
        SG_LOG(SG_GENERAL, SG_ALERT,
               "AI error: checking ATC instruction for aircraft without traffic record");
    } else {
        return i->hasInstruction();
    }
    return false;
}


FGATCInstruction FGApproachController::getInstruction(int id)
{
    TrafficVectorIterator i = activeTraffic.begin();
    // Search search if the current id has an entry
    // This might be faster using a map instead of a vector, but let's start by taking a safe route
    if (activeTraffic.size()) {
        //while ((i->getId() != id) && i != activeTraffic.end()) {
        while (i != activeTraffic.end()) {
            if (i->getId() == id) {
                break;
            }
            i++;
        }
    }
    if (i == activeTraffic.end() || (activeTraffic.size() == 0)) {
        SG_LOG(SG_GENERAL, SG_ALERT,
               "AI error: requesting ATC instruction for aircraft without traffic record");
    } else {
        return i->getInstruction();
    }
    return FGATCInstruction();
}


ActiveRunway *FGApproachController::getRunway(string name)
{
    ActiveRunwayVecIterator rwy = activeRunways.begin();
    if (activeRunways.size()) {
        while (rwy != activeRunways.end()) {
            if (rwy->getRunwayName() == name) {
                break;
            }
            rwy++;
        }
    }
    if (rwy == activeRunways.end()) {
        ActiveRunway aRwy(name, 0);
        activeRunways.push_back(aRwy);
        rwy = activeRunways.end() - 1;
    }
    return &(*rwy);
}