Narrative:

I was a wingman of a section (2) of military T45 jet trainers whose mission was to practice combat reconnaissance with mock attacks on targets of opportunity. This mission requires maneuvering within an altitude block from 3000 ft to 9000 ft MSL on a military training route. This is a common mission I have flown over 50 times in the past 2 yrs, and that aircraft from NAS kingsville fly on a daily basis. The situation is we filed, as identify, for the IR147 military training route and received the usual clearance (stereo route). The clearance was climb to 8000 ft direct to point 'a' of IR147, thence IR147 (a-g) then IFR back to nqi. On takeoff we climbed to 8000 ft and reported to kingsville ATC. Kingsville ATC reported 'you are cleared onto the IR147 route and altitudes.' we asked for a 'descent to 4000 ft' to point a (IR147) to facilitate route entry. Kingsville ATC then coordinated with ZHU and gave us 'maintain below 5000 ft.' we reported leaving 8000 ft for 4000 ft. Kingsville repeated 'maintain below 5000 ft,' we replied leaving 8000 ft for 5000 ft. We then switched to ZHU 322.5 and checked in. ZHU asked if we were cleared on the IR147 and we acknowledged 'affirmative.' just prior to point a IR147 ZHU said 'switch to tactical frequency approved, contact ZHU 307.2 for clearance across VFR corridor.' the VFR corridor is stated in the FLIP for IR147 as the VFR corridor between 2 MOA's, and that if ZHU cannot be reached that we are to transit across between 3000 ft and 5000 ft. This is a corridor between points C and D. At point C we contacted ZHU on 307.2 and 'requested clearance across VFR corridor.' ZHU responded by saying 'maintain below 5000 ft.' we then crossed the VFR corridor between 3000-5000 ft and after turning at point D, initiated a climb above 5000 ft (thinking we had the published altitude block of 3000-9000 ft). ZHU immediately called us (we were monitoring the frequency, although not required to) and ZHU reported a deviation and asked us to contact him on landline. The communication problem is based on the difference in perception between what was thought to have been passed and what was thought to have been received. ZHU by lrd coordinated with kingsville ATC to give us an altitude restr on the IR147 route, but somehow this was not communicated effectively to the flight. Kingsville ATC just instructed us to 'maintain below 5000 ft' when we asked for a descent to 4000 ft to facilitate route entry (which is common on every flight from kingsville for this route). We assumed the clearance was to maintain below 5000 ft in connection to its request for descent to 4000 ft until the start of the IR147. At point a, we assumed we were cleared for the IR147 route and block altitudes (which kingsville ATC had previously cleared). When we asked for clearance across the VFR corridor, the standard FLIP clearance was assumed, and ATC did not elaborate on the restr to maintain below 5000 ft. So when the flight was clear of the VFR corridor, it resumed the normal altitude block in the FLIP, as is normally done on a daily basis. ZHU ATC had an aircraft holding at 6000 ft near the route and the computer recorded a deviation due to the altitude conflict. Communication is a 2-WAY street, and perceptions can cloud communications if they are not clear and understandable, it is ATC's responsibility to assure communications are understood by the receiver, and pass clear and brief reasons for restrs if they are imposed. This will lead to a safer system.

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Original NASA ASRS Text

Title: FLT OF 2 T45'S ARE CLRED TO 'MAINTAIN BELOW 5000 FT.' THEY MISUNDERSTAND AND THINK THAT IS ONLY DURING PASSAGE OF A VFR CORRIDOR AND WHEN CLR OF THE CORRIDOR, THEY BEGIN A CLB TO 9000 FT AS THEY WERE ORIGINALLY CLRED FOR A BLOCK 3000-9000 FT. THEY WERE CONFUSED BY THE 'BELOW 5000 FT' CLRNC. A CONFLICT ENSUED.

Narrative: I WAS A WINGMAN OF A SECTION (2) OF MIL T45 JET TRAINERS WHOSE MISSION WAS TO PRACTICE COMBAT RECONNAISSANCE WITH MOCK ATTACKS ON TARGETS OF OPPORTUNITY. THIS MISSION REQUIRES MANEUVERING WITHIN AN ALT BLOCK FROM 3000 FT TO 9000 FT MSL ON A MIL TRAINING RTE. THIS IS A COMMON MISSION I HAVE FLOWN OVER 50 TIMES IN THE PAST 2 YRS, AND THAT ACFT FROM NAS KINGSVILLE FLY ON A DAILY BASIS. THE SIT IS WE FILED, AS IDENT, FOR THE IR147 MIL TRAINING RTE AND RECEIVED THE USUAL CLRNC (STEREO RTE). THE CLRNC WAS CLB TO 8000 FT DIRECT TO POINT 'A' OF IR147, THENCE IR147 (A-G) THEN IFR BACK TO NQI. ON TKOF WE CLBED TO 8000 FT AND RPTED TO KINGSVILLE ATC. KINGSVILLE ATC RPTED 'YOU ARE CLRED ONTO THE IR147 RTE AND ALTS.' WE ASKED FOR A 'DSCNT TO 4000 FT' TO POINT A (IR147) TO FACILITATE RTE ENTRY. KINGSVILLE ATC THEN COORDINATED WITH ZHU AND GAVE US 'MAINTAIN BELOW 5000 FT.' WE RPTED LEAVING 8000 FT FOR 4000 FT. KINGSVILLE REPEATED 'MAINTAIN BELOW 5000 FT,' WE REPLIED LEAVING 8000 FT FOR 5000 FT. WE THEN SWITCHED TO ZHU 322.5 AND CHKED IN. ZHU ASKED IF WE WERE CLRED ON THE IR147 AND WE ACKNOWLEDGED 'AFFIRMATIVE.' JUST PRIOR TO POINT A IR147 ZHU SAID 'SWITCH TO TACTICAL FREQ APPROVED, CONTACT ZHU 307.2 FOR CLRNC ACROSS VFR CORRIDOR.' THE VFR CORRIDOR IS STATED IN THE FLIP FOR IR147 AS THE VFR CORRIDOR BTWN 2 MOA'S, AND THAT IF ZHU CANNOT BE REACHED THAT WE ARE TO TRANSIT ACROSS BTWN 3000 FT AND 5000 FT. THIS IS A CORRIDOR BTWN POINTS C AND D. AT POINT C WE CONTACTED ZHU ON 307.2 AND 'REQUESTED CLRNC ACROSS VFR CORRIDOR.' ZHU RESPONDED BY SAYING 'MAINTAIN BELOW 5000 FT.' WE THEN CROSSED THE VFR CORRIDOR BTWN 3000-5000 FT AND AFTER TURNING AT POINT D, INITIATED A CLB ABOVE 5000 FT (THINKING WE HAD THE PUBLISHED ALT BLOCK OF 3000-9000 FT). ZHU IMMEDIATELY CALLED US (WE WERE MONITORING THE FREQ, ALTHOUGH NOT REQUIRED TO) AND ZHU RPTED A DEV AND ASKED US TO CONTACT HIM ON LANDLINE. THE COM PROB IS BASED ON THE DIFFERENCE IN PERCEPTION BTWN WHAT WAS THOUGHT TO HAVE BEEN PASSED AND WHAT WAS THOUGHT TO HAVE BEEN RECEIVED. ZHU BY LRD COORDINATED WITH KINGSVILLE ATC TO GIVE US AN ALT RESTR ON THE IR147 RTE, BUT SOMEHOW THIS WAS NOT COMMUNICATED EFFECTIVELY TO THE FLT. KINGSVILLE ATC JUST INSTRUCTED US TO 'MAINTAIN BELOW 5000 FT' WHEN WE ASKED FOR A DSCNT TO 4000 FT TO FACILITATE RTE ENTRY (WHICH IS COMMON ON EVERY FLT FROM KINGSVILLE FOR THIS RTE). WE ASSUMED THE CLRNC WAS TO MAINTAIN BELOW 5000 FT IN CONNECTION TO ITS REQUEST FOR DSCNT TO 4000 FT UNTIL THE START OF THE IR147. AT POINT A, WE ASSUMED WE WERE CLRED FOR THE IR147 RTE AND BLOCK ALTS (WHICH KINGSVILLE ATC HAD PREVIOUSLY CLRED). WHEN WE ASKED FOR CLRNC ACROSS THE VFR CORRIDOR, THE STANDARD FLIP CLRNC WAS ASSUMED, AND ATC DID NOT ELABORATE ON THE RESTR TO MAINTAIN BELOW 5000 FT. SO WHEN THE FLT WAS CLR OF THE VFR CORRIDOR, IT RESUMED THE NORMAL ALT BLOCK IN THE FLIP, AS IS NORMALLY DONE ON A DAILY BASIS. ZHU ATC HAD AN ACFT HOLDING AT 6000 FT NEAR THE RTE AND THE COMPUTER RECORDED A DEV DUE TO THE ALT CONFLICT. COM IS A 2-WAY STREET, AND PERCEPTIONS CAN CLOUD COMS IF THEY ARE NOT CLR AND UNDERSTANDABLE, IT IS ATC'S RESPONSIBILITY TO ASSURE COMS ARE UNDERSTOOD BY THE RECEIVER, AND PASS CLR AND BRIEF REASONS FOR RESTRS IF THEY ARE IMPOSED. THIS WILL LEAD TO A SAFER SYS.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.