Narrative:

Lead aircraft x-venom was climbing to FL310, wingman Y-MIG17, was lagging by 2000 ft, 1 mi. As lead arrived at FL310 and may or may not have called level FL310, wingman Y called center and advised center that he was lagging by 2000 ft because of being heavier. Center advised to call level when both aircraft were level at FL310. X complied and remainder of flight was uneventful. Later, aircraft Y was advised to call and talk with watch controller. Callback conversation with reporter revealed the following information: the lead aircraft was a DH-112 venom, a follow-up type of the vampire. The wing aircraft was a mig-17 fulcrum. The pilot of the mig-17 was the one that filed the mig flight of 2 formation flight plan and had planned to be in the lead, but a lead swap was made as the venom pilot was more tired than the mig pilot. Because of a frontal situation and temperatures aloft, the heavier mig climbed more slowly behind the venom. The mig finally caught up to the venom just as the exchange with ATC was going on about the altitude spread of 32000 ft and the transponder being operative on the wing aircraft. Reporter in the mig said he had no idea he was that much lower because of haze at FL290 with both act having a nose-up attitude. Reporter feels that there was a radar display problem that created a partial confusion in the center. The controller on duty was relatively new according to the next controller they spoke with. Controllers were concerned because formation flts are to be within 100 ft of each other. Reporter received a letter from the FAA asking for aircraft's certification.

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Original NASA ASRS Text

Title: A FORMATION FLT OF A LEAD DEHAVILLAND DH-112 VENOM AND A WING MIG-17 FULCRUM IS QUESTIONED BY ZOB CTLR ABOUT THEIR ALT SPREAD WITH THE WINGMAN BEING 2000 FT BELOW LEAD DURING CLB NEAR ELKINS, WV.

Narrative: LEAD ACFT X-VENOM WAS CLBING TO FL310, WINGMAN Y-MIG17, WAS LAGGING BY 2000 FT, 1 MI. AS LEAD ARRIVED AT FL310 AND MAY OR MAY NOT HAVE CALLED LEVEL FL310, WINGMAN Y CALLED CTR AND ADVISED CTR THAT HE WAS LAGGING BY 2000 FT BECAUSE OF BEING HEAVIER. CTR ADVISED TO CALL LEVEL WHEN BOTH ACFT WERE LEVEL AT FL310. X COMPLIED AND REMAINDER OF FLT WAS UNEVENTFUL. LATER, ACFT Y WAS ADVISED TO CALL AND TALK WITH WATCH CTLR. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE LEAD ACFT WAS A DH-112 VENOM, A FOLLOW-UP TYPE OF THE VAMPIRE. THE WING ACFT WAS A MIG-17 FULCRUM. THE PLT OF THE MIG-17 WAS THE ONE THAT FILED THE MIG FLT OF 2 FORMATION FLT PLAN AND HAD PLANNED TO BE IN THE LEAD, BUT A LEAD SWAP WAS MADE AS THE VENOM PLT WAS MORE TIRED THAN THE MIG PLT. BECAUSE OF A FRONTAL SIT AND TEMPS ALOFT, THE HEAVIER MIG CLBED MORE SLOWLY BEHIND THE VENOM. THE MIG FINALLY CAUGHT UP TO THE VENOM JUST AS THE EXCHANGE WITH ATC WAS GOING ON ABOUT THE ALT SPREAD OF 32000 FT AND THE XPONDER BEING OPERATIVE ON THE WING ACFT. RPTR IN THE MIG SAID HE HAD NO IDEA HE WAS THAT MUCH LOWER BECAUSE OF HAZE AT FL290 WITH BOTH ACT HAVING A NOSE-UP ATTITUDE. RPTR FEELS THAT THERE WAS A RADAR DISPLAY PROB THAT CREATED A PARTIAL CONFUSION IN THE CTR. THE CTLR ON DUTY WAS RELATIVELY NEW ACCORDING TO THE NEXT CTLR THEY SPOKE WITH. CTLRS WERE CONCERNED BECAUSE FORMATION FLTS ARE TO BE WITHIN 100 FT OF EACH OTHER. RPTR RECEIVED A LETTER FROM THE FAA ASKING FOR ACFT'S CERTIFICATION.

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.