Tail wind... on B737-900

[cmcjma]

Hi everyone,
Hope that the right forum for this question.

Since I started to learn how to fly, I learned that the max tail wind speed is 10 kt.
Today, flying the B737-900, I was said the aicraft can be landed or took of with a 15 kt max tail wind.
1) it is definitely in the limitation chapter of the FCOM.
2) it is also in the AFM (section 1, page 4) but, I would like to re-transcript word by word what it is written:
------------------------------------
Maximum Takeoff and landing Tailwind component -- 15 knots

NOTE:
The capability of this airplane has been satisfactorily demonstrated for takeoff and manual landing with tailwinds up to 15 knots. This finding does not constitute operational approval to conduct takeoffs or landings with tailwind components greater than 10 knots.
-------------------------------------

Can someone explain to me the meaning of the last NOTE sentence. It seems to me highly contradictory with the limitation in the FCOM and the above first line in the AFM. What I understand is that the aircraft has been tested up to 15 knots, but it is operationally approved for 10... ONLY!

I am wrong or is it my english understanding level?

Thanks in advance for your comments.

[bobwi]

I was wondering the same thing. The other day we were stuck at an airport because were only aloud to use the runway in one direction and we couldn't because of the maximum tailwind component.

So we explained our delay to our passengers and the next thing that happened is that a 737-800 on our right hand side accepted the tailwind and left.

Some of our pax noticed that and questioned our explanation. Then a 767 on our left told the tower they could accept the steady 15 knot tail wind and left....

Some of our passengers acused us of lying.

But do these boeing airplanes have higher tailwind limitations? Or were they just "flexible" pilots?...

the aircraft has been tested up to 15 knots, but it is operationally approved for 10

Maybe that is because of the 50% margen that is required by law...

[cmcjma]

As far I remember, all the -800 are not certified for 15 kts...
The -800 FCOM stated YD042 - YD045, YK402, YK406: 15 knots
YC126 - YC978, YD216 - YJ953, YK701 - YL052: 10 knots.

For the -900, it seems All are certified.
Now, I do not want to know if the pilots you are talking about are flexible or not.

But, the point regarding my first post is the contradiction it seems there is between the statements in the different manuals

[Johnny Tightlips]

On our -800's we can take a 15kt tailwind on certain approved runways only. Everywhere else it's 10kts.

[mutt]

On our B777 aircraft we were offered and accepted a Specification Change Notice that permitted us to use 15 kts tailwind. As this was during the purchase discussions, it was not a chargeable item.

However, our company operations specifications state 10 kts tailwind limit approved by our regulator. So the aircraft operates with the 10kt limit. That is basically what Boeing is telling you, we have tested 15kts but It's up to YOUR authorities to approve its use.

Mutt

[AIRCON99]

To me this means that the aircraft 'can' take off and landing with a 15 knot tailwind but operationaly it should be limited to 10knots.

For example a lift (elevator) cable probably has a stress limit of thousands of kgs but operationaly they limit the load capacity to a few hundred kgs. The cable can take the strain but that doesnt mean it is a good idea to take it to the limits.

[dispatchshmoe]

Plus, also keep in mind that the runway needs to be of a length where a 15kt tailwind is operationally acceptable.

And you have to have the airport analysis stating that a 15kt tailwind is acceptable, and a light-enough takeoff weight to be able to make a 15-kt tailwind takeoff, since such a tailwind will be very weight limiting. At my first dispatch job, we had one airplane (a BAe146-100) with a 15-kt tailwind limitation, at 1 airport (Aspen, CO, USA).

[cmcjma]

I have one answer, regarding the contradictions between FCOM and AFM as it is stated in the FCOM 0.2.2:
<< The manual is periodically revised to incorporate pertinent procedural and systems information. Items of a more critical nature will be incorporated in operational bulletins and distributed in a timely manner. In all cases, such revisions and changes must remain compatible with the approved AFM with which the operator must comply. In the event of conflict with the AFM, the AFM shall supersede.>>

So now the AFM is clear. As some of you stated it, the aircraft has been tested to 15 kts tail wind (considering RWY length, etc.), but is not approved for 15 kts tail wind in operations.

Thanks to everyone for your comment.
Greetings

[Biggles78]

Surely the max tailwind speed is going to vary per aircraft and maybe even between types plus the company SOP. During training the good old PA28 had a 10kt tailwind component.

Airshow at Ohakea NZ many years ago, visiting US Airforce pilot was asked if they could still perform the same display if they had to change runways. Hell, he said, the F15 can handle a 50kt tailwind.

My understanding that the tailwind component factor was due to the extra speed the types were subjected to and the possibility of delamination due to this extra speed abuse. Sorry, no reference to back this up, just an article from a safety magazine that stuck in my mind.