Accident Report: Toe taps

That’s prudent—but are there any operational considerations that should come to mind now, before you make that next takeoff attempt?

Another scenario to ponder. It is 95 degrees Fahrenheit with almost no wind on the ground at a large airport, with its network of taxi routes requiring numerous changes of direction. Given the location of the FBO you use, you’ve got a long way to taxi after landing. At recommended taxi speed and engine power, this is going to take a while. So you decide to speed things up a little bit by taxiing a little faster than usual. What could go wrong?

A number of things, actually, including loss of control, overheating your air-cooled engine, or damaging the brake system. There’s even a risk of the brakes catching fire—and don’t imagine that to mean merely a smoking main wheel or two and some embarrassing drama on the ramp. It could burn down your airplane.

Not only could it happen, it has happened—quite a price to pay for saving a little time during ground operations, or overlooking the need to cool your brakes after heavy use.

On July 10, 2013, a Cirrus SR22 was substantially damaged after experiencing a brake fire while taxiing after landing at George Bush Intercontinental Airport in Houston.

According to the National Transportation Safety Board’s accident summary, the airline transport pilot landed on Runway 27 and taxied to a fixed-base operator, where employees “reported to air traffic control tower personnel that the airplane appeared to be on fire. The pilot exited the airplane and the fire consumed portions of the fuselage and cockpit.”

Technology left little to guesswork when investigators looked into what had happened. Downloaded data from the aircraft’s primary flight display (PFD) and multifunction display (MFD), examined at NTSB laboratories, provided a detailed recap of the landing and ground operations that followed during 3.7 miles of taxiing—including recorded groundspeeds up to 30 knots and engine power settings to 1,600 rpm.

That data led the NTSB to set the probable cause of the fire as “the pilot’s failure to use the proper taxi procedure, which resulted in a brake system fire.” The agency quoted relevant passages from the aircraft pilot’s operating handbook that said, “When taxiing, directional control is accomplished with rudder deflection and intermittent braking (toe taps) as necessary. Use only as much power as is necessary to achieve forward movement.”

And, “Use minimum power to maintain taxi speed. If the 1,000 rpm taxi power limit and proper braking procedures are not observed, the brake system may overheat and result in brake damage or brake fire.”

That accident may seem like an extreme case based on the distance the aircraft had to travel on the ground. Don’t assume that any lesser distance is safely accomplished in the absence of the walking speed that proper taxi technique requires (and which, granted, tries the patience of some pilots).

In a June 20, 2008, brake fire accident in Williston, Florida, a soloing student pilot—operating a Cirrus SR20—had aborted two takeoff attempts after two full-stop landings when the brakes malfunctioned.

“As the airplane exited the runway onto the taxiway, smoke was emanating from under the wings. The student pilot, airport supervisor, and fire department extinguished fires on both main landing gear,” said the accident report.

Again, data from PFD and MFD sources recorded excessive groundspeeds and power, and the NTSB contrasted them with manufacturer’s recommendations that were not observed. “The student pilot also did not comply with the safety information section in the POH, which recommended adequate cooling time for the brakes after heavy use,” it said.

There’s no time like the present to review your own aircraft’s POH for operating and safety techniques—a far better choice than becoming the protagonist in a scenario that brings your flying to a screeching halt.

Normal taxi should be slow enough that when the throttle is closed, the airplane can be stopped promptly. 

On the test

Taxi standards

According to the private pilot airmen certification standards, applicants must “control direction and speed without excessive use of brakes” and demonstrate understanding of “good cockpit discipline during taxi, including maintaining a sterile cockpit, proper speed, separation between other aircraft and vehicles, and communication procedures.”