Aborted take off AFM actions.

[Centaurus]

With regard to the aborted take off handling for the B737. If the order of actions for a rejected take off procedure is mandated in the AFM, then why would some airlines differ in opinion as to the order of actions, and require their crews to operate to the Company Operations Manual procedure rather than the AFM mandated procedure?

Example being, that Boeing require manual speed brake extension before actuation of reverse thrust. Correct application of reverse thrust will also extend the speed brake providing the automatic function of the speed brake works. However, some companies direct that reverse thrust should be used as the first means of actuating the speed brakes.

In practice there is very little time difference between manual speed brake actuation and use of reverse to actuate the speed brake. But there must be a very good reason why Boeing recommend manual speed brake first and not rely on the reverse levers to actuate the speed brakes.

If the Boeing action for rejected take off is published in the AFM, then is it illegal for companies to mandate otherwise in the company operations manual?

I do not have a copy of a 737 AFM, and I was wondering if anyone can tell me if the actions for an abort are specified in the typical 737 AFM?

[alf5071h]

The manufacturers procedures are usually well thought-out; the implementation by regulator or operator not always so, e.g. some Regulators declare manufacturers ‘advice’ (non mandatory guidance in manufacturers operations manual) as mandatory in lieu of independent thought (and escaping the lawyers).

If the AFM contains ‘mandated’ procedures then there are good reasons for them; the manufacture is usually guilty of not explaining these reasons in other documentation. AFM procedures are the legal requirements and must be followed; only the manufacture or regulator can change these or give a dispensation.

Many aircraft with auto deployed systems require a manual follow up to counter system failure (which could be the reason for an RTO), or operating error. The sequence of a procedure may consider the ease or time of the crew selection, or the timing of an ‘automatic’ interlock to be made, e.g. time for the engine spool-down before reverse can be selected.

Other considerations may include the effectiveness of the retarding device (normally brakes are the best), or the certification requirements where the certificated stopping distance is not always dependent on the use of reverse, whereas spoilers are. Also the logic in using controls is considered; it may be easier to continue to hold the thrust levers after retardation in order to engage reverse and modulate the thrust level.

Check the wording carefully between AFM and manufactures ops manual, ask the manufactures advice, try to educate the regulator, and always stand on the brakes.

[Shawn Coyle]

I beg to differ on the "AFM Procedures are legal requirements".
The only section of the flight manual (and the FCOM or other documents based on the AFM) you must follow is the limitations section. It says so in the beginning of the Limitations section, and in the Type Certificate Data Sheet and Airworthiness Certificate.
The normal, abnormal and emergency procedures have no such wording at the beginning of their sections. (Beech manuals notwithstanding - they claim everything is mandatory...). Ergo, it is not mandatory to follow them.

The rub comes in company approved procedures manuals, which are required to be followed by the operating rules. If it's in the approved operations manual, then the company can insist that this is the way to do things. That's different than the airworthiness or engineering certification requirements.
But there is no requirement in the original approved flight manual (the one that says FAA approved on the bottom of the page) to follow only the normal or emergency procedures as written in the manual.

You should have a pretty good reason to not follow it, and sometimes people make the changes without having thought them through as well as they should.

[alf5071h]

Shawn, each of our views is correct. The differences occur in the definition of the AFM. I am more familiar with the UK CAA manual than the FAA AFM, but I have written and worked with both, although several years ago.

The UK view was that the AFM was the legal document to the extent that not even an inspector could over-ride it without higher approval. The manufacturer’s ops manual (FCOM) gave additional operating information, which often duplicated the AFM information to retain clarity. More recently, some European countries have dispensed with a separate AFM and only use the FCOM, but I do not know how the AFM (legal) content is identified within the FCOM. This could be a further source of confusion.

The FAA AFM tended towards the combined European manual, which included the type data sheet (mandated material) and the manufacturer’s recommendations. A local inspector could approve a change to the latter information. Thus, there was an opportunity for a representative of the regulator to overrule the manufacturer with obvious safety implications. I spent considerable time heading off many potential trouble spots.

I total agree with your last statement.

“Unless specifically authorised, everything else is prohibited”; attributed to the French certification philosophy.

[Shawn Coyle]

An interesting sticking point - also what I call a bit of regulatory creep (not be confused with lounge lizard or other low life).
If you go to the Type Certificate Data Sheet, which is the basis for the Certificate of Airworthiness, you'll see that there are limitations listed there. It says nothing about the normal and emergency procedures having to be followed.
So for someone to insist that the flight manual procedures must be followed would make it nearly impossible to handle modifications to the aircraft such as STCs or possibly even in the USA, form 337 changes - especially if they change the operating procedures - it would mean that literally, you would have to republish the entire procedures section in the supplement for the FM.
The FCOM, in my experience, is just a compliation of all the mods and STCs to an airframe for a manufacturer, and will contain all the required information from the AFM and supplements, put into one manual. BUt somewhere, lurking in a dim and dusty closet will be original AFM and supplements.

[Centaurus]

Thank you all very much for the information so far. I still cannot get my mitts on a 737 AFM as I do not work for a specific airline who has 737's. But I am still curious to find out if the rejected take off sequence is published in the AFM.