ASRS Directline

  Issue Number 1 : March 1991

There I Was... At Least I Thought I Was: Advanced Technology Aircraft

by Mike Smiley

Recently an incident was reported to ASRS that emphasizes the need for flight crews flying advanced technology aircraft to back up the computer-generated route and navigation database with "old fashioned" navigation charts. Let's examine this incident through the eyes of the reporting flight crew:

A rare occurrence? An isolated event? Not at all! You can find related incidents in the ASRS database spanning many years and involving virtually every phase of flight.

Phase of Flight

Departure Phase

The flight crew sums it up--"Problems of this type can only be avoided through greater vigilance and a commitment to use whatever caution necessary to avoid such errors; one must avoid undue dependency on computer generated flight paths."

Enroute Phase

The enroute phase is the phase of flight where technology has supposedly all but eliminated workload. Or has it?

Descent Phase

Descent and crossing fixes add their share to the dilemma:

Approach Phase

Even the approach phase is not immune from track errors, although this is usually where the crew is very alert:

ATC Involvement

Sometimes re-programming woes appear to be caused by a combination of ATC not understanding flight crew workload, and the flight crew not being ready for changes. ATC clearance amendments that are not on the FMC route of flight can pose significant workload increases for flight crews flying advanced technology aircraft, even when the flight crew is able to comply. If the clearance change is received when the workload is already high, such as immediately prior to takeoff, the result can be even more dramatic:


As we all know, today's ATC environment is getting more congested and complex. Advanced technology aircraft systems, though reliable, are not perfect and will occasionally malfunction. A sure defense against this condition is to have all appropriate charts available. Additionally, if any difficulty is encountered in programming or utilizing automated flight management systems, don't hesitate to take manual control of the aircraft and fly it where you are supposed to go. Implement these two simple rules and you will avoid, " least I thought I was there."

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