The jet crew had shut down an engine and was busy running checklists for single-engine operations when air traffic control radioed to ask “if the cockpit is secure.”
“That's when I looked down, noticed the mistake and dialed in 7700,” explained one pilot in an Aviation Safety Reporting System filing about the error-by-distraction that occurred while the crew had its hands full safely completing a single-engine approach.
Mostly regarded as a set-and-forget component of an aircraft’s avionics, a transponder, with its multiple modes and codes, still demands attentive operation.
The error described above was quickly corrected. But consider that when the pilot is not in radio contact with ATC, a mistake can go undetected for a long time, as more than one chagrined pilot has realized before filing an apologetic ASRS report.
Here’s another not-uncommon scenario: You come out to the airport to fly a club or rental aircraft, and perform your usual preparations—only to discover after takeoff that the transponder is still set to a code assigned to the previous flight. (This is less likely to happen if you requested radar flight following and were assigned a new code before takeoff.)
Keep the transponder in mind on your own multiple-leg flights. A pilot who performed practice instrument approaches with an assigned transponder code took a break for dinner before heading home under VFR. But the pilot forgot to reset the transponder to code 1200 for the VFR return flight.
Don’t compound a code error with a mode error. Another ASRS report revealed how a pilot doubled down on distraction by putting a transponder that had been squawking the wrong numbers in standby mode while correcting the code—but then forgetting to switch the unit out of standby, resulting in ATC losing track of the flight.
AOPA recently received email from a worker in an air defense facility who became concerned after observing “several mistakes,” and wrote to suggest that pilots spend some time brushing up on transponder operations.
“We pilots should ensure each switch we touch or lever we pull is done purposefully and accurately,” the observer noted.
Weigh in on this training topic at AOPAHangar.com.