diff --git a/tar1090.sh b/tar1090.sh
index 2403476..0f2cb8e 100755
--- a/tar1090.sh
+++ b/tar1090.sh
@@ -76,7 +76,7 @@ prune() {
 	jq -c <"$1" >"$2" '
 		.aircraft |= map(select(has("seen") and .seen < 15))
 		| .aircraft[] |= [.hex,
-		(if .alt_baro != null then .alt_baro else .alt_geom end),
+		(if .alt_baro != null then .alt_baro elif .altitude != null then .altitude else .alt_geom end),
 		(if .gs != null then .gs else .tas end),
 		.track, .lat, .lon, .seen_pos,
 		(if .mlat != null and (.mlat | contains(["lat"])) then "mlat"