October 14, 2015
We recently had an incident involving two AMFA members while taxiing an aircraft that resulted in an aircraft being damaged. This incident has resulted in many conversations regarding what should or should not happen while taxiing an aircraft. This article in no way references the details of the above mentioned incident, rather its purpose is to clarify some of the proper procedures of taxiing an aircraft.
I would first like to discuss the phrase or command “without delay.” After discussing this phrase with an Air Traffic Controller (ATC) member, I would like to take this opportunity to offer further explanation and clarification. This phrase indicates a severe request. “Expedite” is also used by ATC when prompt compliance is required to avoid the development of an imminent situation. These phrases are similar but “without delay” is not in the AIM or in the ATC Glossary; however, it is mentioned in the Air Traffic Organization Policy and can be used interchangeably with expedite. Expedite is imminent danger, very similar to without delay which is severe, but is considered by ATC as more urgent. Always remember if you cannot move quickly, deny movement and request to stay or wait. “Taxi without delay,” means, move your tail. With this request you should offer a polite acknowledgment, and increase your taxi to no faster than the FAA’s mandated speed of a fast walk or whatever your procedures allow, or deny the movement.
Some other similar phrases that you might hear at different airports meaning the same thing are: PDQ, at once, directly, expeditiously, forthwith, immediately, in a hurry, in no time, instantly, now, on the instant, on the spot, pretty damned quick, promptly, pronto, quickly, right away, right now, smartly, speedily, straightaway, swiftly, this minute, without further delay. These phrases can all mean the same thing and have the same actions tied to them involving an imminent situation. Stop the aircraft and request ATC clarification if there is any confusion.
If the aircraft is stopped, higher power settings and additional time may be required to get the aircraft moving. It may not be prudent to accept a clearance for an expedited runway crossing. Do not use excessive break away power. Southwest Airlines (SWA) is limited to 35% N1 on single engine taxi and states, “Use caution when exceeding 35% N1,” and Alaska Airlines (ASA) is at 65% N1 while taxiing the aircraft. Smoothly advance the thrust to begin taxi. Retard throttle to idle when practical after the aircraft begins to move. It is not recommended to operate both engines at high power (above 75% N1) simultaneously at any time. Don’t slam the throttles as the NG sees the demand and when it catches up the advance load is already provided as it results in higher speed than intended.
Both companies also require you to align IRS to display ground speed and to wear seatbelts, which is contained in the checklist. You must have a checklist at all times while taxiing and a current Jeppesen airport chart must be used. This checklist must be used by maintenance employees for all taxi and/or engine operations. A cultural norm should be to use the checklist .The Aircraft Maintenance Technician (AMT) must verbally call out the challenge and then perform the action and respond. All movements and indications are recorded in DFDR and also CVR is in operation and records all conversations; therefore, there should also be a sterile cockpit, only essential communication needed.
Maintenance taxi operations are performed at speeds allowing safe operation and control of the aircraft under existing surface and/or weather conditions. ASA allows a taxi speed not to exceed 60 knots for maintenance taxi check; however, states never to exceed 40 knots on a taxiway. The SWA taxi checklist states maximum taxi speed is approximately 20 knots unless directed to expedite by an ATC. Maintain a safe taxi speed commensurate with actual runway and weather conditions and anticipated braking action at the end of the runway or taxiway. Be aware that it is easy to overestimate the cornering and braking ability of the aircraft. It may be necessary to slow to taxi speeds as low as 5 knots when preparing to exit the runway or turn from a taxiway. It is a good policy to not exceed 20 knots and 12 to 8 knots in turns unless conditions dictate otherwise.
Any person knowingly deviating from these policies and procedures or operating an aircraft in a reckless and unsafe manner may have his Engine Taxi/Engine Run-up Certification revoked and may be subject to termination. AMT work culture has always been, “do whatever it takes to get it done,” however, we must follow proper policies and procedures. Don’t put pressure on yourself to expedite your task or to not properly follow procedures. These are the requirements. Take the time to follow procedures correctly and keep yourself proficient. Familiarize yourself with the safety initiative, our new culture, and follow it. Stay safe!
David A. Brooks
National Safety & Standards Director