diff --git a/src/ATCDCL/ATC.hxx b/src/ATCDCL/ATC.hxx
index 2b8a0a933..e5ddcd0a9 100644
--- a/src/ATCDCL/ATC.hxx
+++ b/src/ATCDCL/ATC.hxx
@@ -89,6 +89,7 @@ const int ATC_NUM_TYPES = 1 + INVALID;
 
 // DCL - new experimental ATC data store
 struct ATCData {
+        ATCData() : type(INVALID), cart(0, 0, 0), freq(0), range(0) {}
 	atc_type type;
 	SGGeod geod;
 	SGVec3d cart;
@@ -101,6 +102,7 @@ struct ATCData {
 // perhaps we could use an FGRunway instead of this.
 // That wouldn't cache the orthopos though.
 struct RunwayDetails {
+        RunwayDetails() : end1ortho(0, 0, 0), end2ortho(0, 0, 0), hdg(0), length(-1), width(-1) {}
 	SGGeod threshold_pos;
 	SGVec3d end1ortho;	// ortho projection end1 (the threshold ATM)
 	SGVec3d end2ortho;	// ortho projection end2 (the take off end in the current hardwired scheme)