OPS topics

Flying Safety, August, 2004

Here are few more examples of miscommunication and aircraft operators. We need less HATRs and more communication!

Who Controls What?

A student on a solo was taxiing out for a contact mission. En route to the "T-37" Runway 33R, he would have to cross Runway 33L and 33C. Normally, the tower controls 33C, and Runway 33L is controlled by T-38 RSU. While taxiing towards 33L, the student "thought" he heard another aircraft being cleared to cross Runway 33L and 33C by tower. This led the student to believe tower was controlling both runways. The student approached Runway 33L at Taxiway Golf, which is approximately 6000 feet from the threshold of Runway 33L. Before he had changed to the T-38 RSU frequency, tower cleared another aircraft to cross Runway 33C. Mistaking this as his clearance to cross Runway 33L, he proceeded to cross the runway. As he was making his way across the runway, he noticed a T-38 on a touch-and-go, and elected to continue to cross so he would not block the runway. The T-38 was airborne again approximately 2000 feet prior to Taxiway Golf, and the student was clear of the runway just as the T-38 passed him. This HATR was not listed as "pilot error--USAF," therefore, cause is reported to be unknown. One can definitely see the importance of proper radio procedures, especially early on in training.

Takeoff Clearance? Abort? When?

Two T-6As, Aircraft 1 and 2, (A1 and A2) were cleared into takeoff position and told to hold soon after another aircraft was cleared for takeoff and departure. The T-6 flight commenced a wing take-off without clearance. A1 lined up on the right side of the runway with A2 on the left. At approximately 60-70 knots, tower noticed A1 on takeoff roll and stated, "A1, cancel takeoff clearance." Tower made this call because A1 flight did not have adequate IFR spacing with the previously departing aircraft. A1 abruptly aborted the takeoff despite approximately 6000 feet of runway remaining. A1 locked their left brake, and the left tire started skidding. A2 noticed the skid, informed lead and released brakes/added power to pass and thus attain separation from A1. A1 blew their left tire and stopped on the left side of the runway. A2 taxied clear of the runway uneventfully.

The aircrew and tower personnel were interviewed about this incident and their recollections were congruent. Ultimately the aircrew was at fault. They acknowledged a clearance to taxi into position and hold, yet proceeded to take off. Considering there were four rated pilots (two instructors and two students) on board, there was ample opportunity for aircrew intervention. The lead flight crew stated he allowed the student error and ensuing remedial instruction to distract him from the clearance. Aircrew complacency, expectation and misprioritization led to this mistake.

Unfortunately, this type of error is relatively common in aviation, and the only solution this investigator had to offer is to brief other crews of past mistakes. What makes this incident particularly interesting is how the controller chose to handle an aircrew error and made the situation more dangerous. In FY02, two similar incidents took place where aircraft departed without takeoff clearance. In both of those cases, the aircraft did not have adequate IFR separation with the previous aircraft, and the tower controllers uneventfully deconflicted the separation problem airborne. In this case, the controller chose to make a radio call stating "cancel takeoff clearance" when the formation was at a relatively high airspeed. At the time this call was made, the aircrew mistakenly thought they had clearance for takeoff and had no idea why they were being told to stop. The trainee in the lead aircraft overreacted and abruptly aborted, despite ample runway remaining for a more controlled formation abort. There was little time for the instructor to intervene at this point. The trainee's reaction to the controller's radio call could have easily led to a collision between the formation members. Though the aircrew would have been causal, the controller's action would have been considered a contributing factor.

When correcting aircrew errors, controllers need to consider whether the correction needs to be made at the precise moment the error is noticed or at a more appropriate time. This is especially true during the takeoff phase. It's not just how you correct a mistake that is important, but also when you correct it.

Who Do I Call?

The following HATR concerns an Aero Club Cessna 172 taking off without clearance. The C-172 called ground control requesting taxi for his VFR cross-country departure. The aircraft was issued taxi instructions to taxi to and hold short of Runway 19 at Taxiway November. The aircraft taxied for the intersection departure at Taxiway November and performed his engine runup. Soon afterwards, the tower controller noticed the Cessna airborne midfield off Runway 19. The tower controller attempted to contact the aircraft repeatedly. The aircraft performed a left downwind departure and proceeded northbound, climbing to approximately 1000 feet MSL. Tower was never able to establish communications with the aircraft, and it exited the Class D airspace to the North.