Pilot error or Design flaw?
Are OEMs making us bite more than we can chew?


Airplane manufacturers under pressure to deliver more efficient airplanes on one hand and manage legal accountability on the other hand are pushing pilots to spots that we might wish could be avoided.

Airline pilots are trained expected and get paid to perform under pressure. Make the right decision manage risks and maneuver through tight spots come what may.

But are manufacturers downplaying the limitations of Human Performance, over emphasizing technical compliance, and ending up missing the mark on both fronts?

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In November 2002 FAR 25.1001 “Fuel jettisoning system” was changed. The new criteria called for new airplanes so that they should be able to jettison fuel for 15 minutes, to meet the climb requirements during a go around. It must be stressed that this is not an operational limitation. It is a design criterion.

The 787 is a great airplane it consumes 25% less fuel while carrying the same number of passengers as a 777. To so its engines are super-efficient during cruise but produce less power during takeoff. There is a real problem for 787 to meet the newly commissioned design criterion. Boeing’s solution was to use the On-Board Performance Tool (OPT) to calculate for each takeoff this requirement and in such cases as high temp high altitude airports limit the takeoff weight. This will happen at high altitude high temp low pressure environment. And is irrelevant for almost 100% of takeoffs. However, the calculation is performed for 100% of takeoffs requiring pilots to key in not only the Takeoff weight but also the ZFW so the SW knows how much fuel is onboard.

This is in total contradiction to all recent studies regarding the vulnerabilities of takeoff-calculations pilot lapses and errors resulting in erroneous takeoff parameters.

Boeing is choosing this way to show meeting the legal requirement of FAR 25.1001 so the 787 can achieve better CASK. (cost per available seat kilometer)

So what is the downside?

On April 28th 2019 Dennis Muilenburg then Boeing’s CEO hinted at pilots competency as the cause for the 737 max accidents, this was a month after the Ethiopian airlines crash. We now know better.

What most of us do not know is that the FAA does not accept any more the notion “that during multiple failures the pilots will have to do on their own”. They now require manufacturers to provide guidelines and solutions for such situatios. The main factors to Maxs crashes in a nutshell are mostly the fact that pilots are taught to fear most of all loss of control due to airspeed indication malfunction, so when the 737 Max introduced both Unreliable airspeed and Runaway Stabilizer together with a boatload of noises and warnings, the crews, overwhelmed, addressed the airspeed issue with a higher priority than the stabilizer problem which was never thought to be a possibility. Pilot were not aware of the MCAS’s possibility to perform that way.

AC-120-71b “Standard Operating Procedures and Pilot Monitoring Duties for Flight Deck Crewmembers” is the industry’s paper on how to establish SOPs considering safety and human performance.

SOPs according to the AC are to be logical, include the needed information to determine the correct procedure is used, avoid visual clutter i.e. avoid TMI, use plain language, use short sentences, Use active verbs and write steps as imperative. What to do not what not to do.

The same AC also states clearly what are the Pilot Monitoring’s tasks – Mainly and above all – monitor the flight path. (The AC originally before versions A or B was mainly published to explain the transition from Pilot Not flying PNF to Pilot Monitoring PM. What one is supposed to do not what they are supposed not to do.

When you read the policy as written by the manufacturers – they put performing and completing ahead of flight path monitoring.

If you look at the Airspeed Unreliable Non-Normal checklist, Pilots are not required to disconnect the Autopilot anymore, we are required to press the button that if no other malfunction exists will disconnect the autopilot.

If you perform this checklist verbatim as written the PM spends a few minutes head down and does not accomplish their primary task of Flight Path Monitoring in a spot that the PF is having a hard time flying the airplane. The checklist is far from user friendly, and you have to review a ton of items most of which might not be relevant.


The same principal applies for the fuel leak NNC and a few more.

The manufacturer De-Facto is overriding the AC’s guidelines of prioritizing cockpit tasks.

However, there is another way. The responsibility to provide SOPs rests with the operator. Not only with the manufacturer. Chapter 2 of the AC draws the guidelines for when a modification to the OEM’s (Original Equipment Manufacturer – Airbus Boeing etc.) is necessary. “They promote optimum use of aircraft features” the AC stops short of saying disregarding human performance stating, “they may be generic” and calls for modifications in such cases as:

New or modified equipment

Changes to the operational environment

Company mandated procedure

Fleet uniformity

Observed operational problems.

Incidents, accidents.


Manufacturers tend to establish SOPs including Checklists that theoretically best utilize all the airplane’s features. Sometimes this is done without enough attention to the limitations of human performance.

It is the operator’s responsibility to balance, compliance to OEM’s SOP and human performance as the interests do not totally overlap.

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