Icao Mfra

[de facto]

Dear all,

This bugs me so here I go.
I know that FAA and JAA use a Minimum LEGAL flaps Retraction Altitude of 400ft AGL(to be corrected for low temp) but I cant find any info on the ICAO one.

I was told it is 820 ft but i highly doubt it.
The reason behind the question is our RTOW charts have some MFRA below 820ft (eventhough our SOPS use 1000ft as MFRA if our RTOW Chart MFRA is below 1000ft).For example for the runway in use :MFRA is 600Ft we use 1000ft) I operate under ICAO (China).

If you have the answer please let me know the reference you used.

Regards,

[latetonite]

Regulated MTOW below 1000 ft??? Please elabotate further.

[de facto]

Re edited

[de facto]

What is the minimum legal flaps retraction altitude by ICAO?

Anyone?

[bfisk]

The ICAO doesn't have jurisdiction anywhere. They are an advisory body and it's up to each (member) state to adopt their standards and recommended practices as they see fit. You need to consult the laws that govern you, normally those where the aircraft or AOC are registered.

[de facto]

Thank you Bfisk

Latetonite: What does your airline use as MFRA?400ft? you fly in the gulf?

[latetonite]

We use a 1000 ft agl.

However, I understand l the minimum flap retraction altitude for a take off with engine failure is 400 ft. (FCTM B737)
Boeing uses 1000 ft for training purposes.

[aterpster]

de factro:

I know that FAA and JAA use a Minimum LEGAL flaps Retraction Altitude of 400ft AGL(to be corrected for low temp) but I cant find any info on the ICAO one.

The FAA wrote the original transport certification rules then JAA joined in later. 400 feet (as a minimum configuration change altitude) is set in concrete by virtual of the certification takeoff flight path.

[de facto]

Latetonite,

My airline also uses 1000ft as Minimum FRA.Which is safer than just using the minimum based on obstacles(ie 600ft).
As far as i know we could accelerate higher (ie1500) as long as you are not TOGA time limited...

The fact than the FCTM (boeing) says 400 ft is the legal minimum FRA (as they are under FAA) doesnt help me to find out whether some ICAO licensing states use higher Minimum MFRA (ie 800ft).


I understand Boeing uses 1000 ft as MFRA for training as it is an easy nr to remember and safe in most airports.

Thanks all for your inputs so far.

[Gulfcapt]

Good topic de facto; this is one of those things that has bothered me as well.

As was discussed by Mad Flt Scientist in this thread http://www.pprune.org/tech-log/42082...aircrafts.html, I think 400'AGL is a certification altitude. I have searched and have never been able to find any reference to 400'AGL anywhere else.

Perhaps Boeing advises 400' OEI vs 1000'AGL for normal ops because the aircraft will not meet the OEI performance requirements if flaps are carried to 1000'AGL?

I used to fly the Gulfstream 2 and 3. On the 2, OEI SOP had us start cleaning things up at or above 400'AGL. However, in the 3 we carried takeoff configuration to 1500'AGL OEI; we were told this was because the 3's OEI performance exceeded the minimum requirements of Part 25. Gulfstream's 1500'AGL OEI profile continues in the 4 and 5.

Unfortunately, Gulfstream has recommended for years that for normal takeoffs the profile is gear up, flaps up. I refuse.

Best,
GC

[de facto]

Aterpeter,

I believe you and it makes sense.

"Perhaps Boeing advises 400' OEI vs 1000'AGL for normal ops because the aircraft will not meet the OEI performance requirements if flaps are carried to 1000'AGL? "

Gulfcapt,

Ok,from what i understand,if you have no obstacles in your take off path(ie you take off from an island and there is water left right and center:-) ) so your perf data will STILL give you a Minimum flaps retraction height of 400ft.
This is a legal requirement cause really you could accelerate at 200 feet...and this what i am interested in...is it the same for all states?(USA,Europe i know but what about Indonesia?china?UAE?).
I grasp the fact that your airline may impose a higher acceleration to be on the safe side...
Accelerating at 400 feet height will give you a clearance of 35ft of the obstacle....but beware of cold altitude corrections...


If there are however obstacles in your take off path(your perf analysis will give you a higher Minimum flaps retraction altitude,lets say 800ft),so it means if you lose an engine you need to climb to a minimum height of 800 feet before accelerating to be above the take off obstacle.
So airlines using a higher MFR height will be on the safer side (ie Runway perf gives you a MFR of (400-999ft).

For the Flaps retraction height you are limited by TOGA time.

Concerning if you are climb limited,it is another story, you may need to use improve climb speeds(to make the oei 2.4% gradient,VLOF to 35 ft dry runway),
which will give you the highest v1 for the runway used.
The scary part is that if you reject at V1, you will be very closed to the end of the runway...dont correct for low Qnh and you go ploof into the water....

"Unfortunately, Gulfstream has recommended for years that for normal takeoffs the profile is gear up, flaps up. I refuse."

Im glad you do..

[aterpster]

F.A.R. 25.111 It is readily available.

[john_tullamarine]

It's easy to get a bit tangled up with this. Points of relevance (and some have been made by others, above) -

(a) the 400ft thing is tied up with AFM OEI profiles and is a consequence of the heavy design Standards

(b) for a given runway, the operator may schedule some higher third segment for terrain optimisation or whatever. In this case, read the higher figure instead of 400ft. It is noted that the maximum retraction height, OEI, usually will be based on either engine operation at rated thrust or some other systems limitation (eg RR Dart powered Types at 600ft - although, just at the moment, I can't bring to mind what the system limit was - autofeather time limit, perhaps ?)

(c) the operator will (should ?) do the sums to make sure that the presumed/declared OEI escape path achieves the usual obstacle clearances

(d) for SID style departures, the AEO case is subject to additional climb/obstacle clearance considerations

(e) providing one respects (c), by operating in a manner that keeps the aircraft above (generally, well above, in practice) the OEI net profile, and (d), for similar considerations, there is nothing, per se, precluding your using a different flap retraction profile for routine AEO departures. Indeed, such is seen in just about every operations manual dotted around the paddock.

(f) one notes that many, if not all, operators, use a standardised departure profile, typically based on the critical runway for the particular operation. This makes a lot of sense for flight standardisation purposes.

[Gulfcapt]

De facto, given that the 400'AGL is a certification requirement (as opposed to an operating requirement) from US FAA, I guess it would depend on whether a given country has their own certification standard or not. You certainly raise an interesting point; maybe somebody else can answer it for us.

I am not familar with the performance characteristics of in production Boeings and AB so what I am about to say may be dated.

Accelerating/cleaning up at 800'AGL vs 400'AGL (in your example) may not be "safer." Older jets (707, Gulfstream 2) needed to clean up at 400'AGL in order to increase their rate of climb. In other words, all other variables constant, cleaning up the older jets at 800'AGL resulted in less altitude gained than if they were cleaned up at 400'. Perhaps this is not a factor anymore; I know its not with the Gulfstream, hence the OEI profile goes to 1500'AGL on the newer models.

I think John T is spot-on with his remarks. Airline operators can taylor their profiles to fit their route structure.

Best,
GC

[john_tullamarine]

Older jets (707, Gulfstream 2) needed to clean up at 400'AGL in order to increase their rate of climb

Absolutely ... but if there is a big lump of granite at 500ft in the third segment, that might not be a good lifestyle strategy ... hence the utility of pushing the third segment a tad higher than 400ft ... if not all the time then, certainly, some of the time.

[willium]

I know that FAA and JAA use a Minimum LEGAL flaps Retraction Altitude of 400ft AGL(to be corrected for low temp) but I cant find any info on the ICAO one.

[Gulfcapt]

John T:

"...but if there is a big lump of granite at 500ft in the third segment..."

Man, I hate those John

Point well taken, but wouldn't that be as per the operator to determine obstacle clearance? OP's question was on minimum legal flap retraction altitude which, I believe, is a certification question.

Bfisk:

"The ICAO doesn't have jurisdiction anywhere. They are an advisory body and it's up to each (member) state to adopt their standards and recommended practices as they see fit. You need to consult the laws that govern you, normally those where the aircraft or AOC are registered"

Concur.

Best,
GC

[HazelNuts39]

Originally Posted by Gulfcapt

De facto, given that the 400'AGL is a certification requirement (as opposed to an operating requirement) from US FAA, I guess it would depend on whether a given country has their own certification standard or not. You certainly raise an interesting point; maybe somebody else can answer it for us.

The operating requirement (in many countries, the country is that of the operator) is that take-off obstacle clearance must be shown on the basis of the OEI net flight path data provided in the Airplane Flight Manual.

The performance data in the AFM are established in accordance with the airworthiness certification regulations, which specify that the OEI net take-off flight data must be based on a procedure which assumes that the take-off flap setting is maintained up to at least 400 ft above the runway altitude.

To my knowledge, all large transport airplanes manufactured in what used to be called the "western" world, are certificated to essentially the same standards as FAR Part 25 or CS-25.

regards,
HN39

[rudderrudderrat]

Edit: Reference removed due Error/

Hi HazelNuts39,

You are correct. I must have skipped a big chunk when I was searching.
Thanks.

[HazelNuts39]

rudderrudderat;

Is this for 'Performance Class B'; propeller-driven, less than 10 pax, less than 5700 kg?