B737-800 Flap speeds
 

Our FCOM contains a phrase: Select Flaps passing through the minimum flap speed on the speed tape. This reduces wear on the flap tracks. Using Flaps as speedbrakes is not recommended"

We operate into an first world airport with third world ATC somewhere in the south of Europe where a visual approach is offered when some 7-8000 above profile. Now we are big boys and have no problem asking or demanding more track miles if needed, that is not the question. The technique I have seen is: LVL CHG, Speedbrake out, speed 230 Kts, Gear down at 260Kts (Max Speed -270kts), Flaps 1 and 5 at 245Kts (Max speed 250Kts). This produces a very steep descent rate and we can regain the profile before 10 miles final.

The max flap speed is 250Kts for 1 and 5 and the minimum clean is 210 kts. We did not breach any aircraft limitations. But is it good practice to operate the aircraft just inside the flap and gear limitations like that?

The answer to you question is NO it is not. Respect limits and be kind to aircraft. In the same way that G-limits on landing is 2G.....we don't routinely aim to land just shy of this....or do we!?

Whilst flap assemblies ARE 'stressed' for the max speeds, the fatigue life assumes they are used more often at 'normal' speeds, hence you do them no favours.

Why not 'plan ahead' and get the profile sorted out for that (expected) visual? Most operators also discourage excessive rates of descent near to MSA which is worth bearing in mind as you drop like a brick:). Often the best way is min clean, gear/flap to approach flap when cleared for the visual (with appropriate flap manoeuvre speeds) and set your company 'limit' on R of D in V/s. The reduced ground speed will help lose the height in the least track miles.

Why accept the visual approach? Why don't ask for a 360 to loose hight? Do you have an ideea about the noise landing gear makes inside the plane when extended at high speed? Do you tell the pax you'll extend the gear,so they should expect very high noise and maybe vibration? I bet not....
So ,again ,why should one accept and perform such a manouvre? We have a strict data monitoring program ,and I suppose after few of these approaches , a talk will take place between the company CIFS and that particular airport officials.
I know that some controllers, and unfortunatelly pilots also , think that we are flying fighters.We are not.

Not really...
 

Telstar,

Next couple of times this happens to you, try to experiement. I think you'll find that the first few increments of flaps/slats add very little drag, and the only thing you're accomplishing is beating up the flaps/slats and the passengers.

This is mainly why Boeing states this is not recommended. You're not really helping yourself. (What you want and need is drag...and you're not getting it with low flap settings.) Boeing has a publication somewhere (I remember reading it years ago.) about energy management in descents. If you can get your hands on this, it'll explain a lot.

The best way to 'slam-dunk' is with gear and speedbrake....keep your speed up a bit. It'll drop like a rock. The other alternative is to grit your teeth, slow up and work out your flaps, then gear, then more flaps (extend flaps on the normal schedule), until you get to approach speed plus a bit. Once you have full flaps, gear, idle thrust, you'll find the thing will come down nicely. (The trick is to be patient while you get to this configuration.) Of course, you must be careful to arrest the sink rate and be spooled at the proper time.

The idea of not using flaps/slats as a speedbrake applies to most airplanes. Again, it's drag you want and need, but flaps/slats don't give you what you need...unless you have everything hanging out.


Fly safe...


PantLoad

Hello first of all, I'm new to the forums first post. I've pondered the rapid altitude loss configurations also, here is the note in the FCTM that says "the use of speedbrakes with flaps extended should be avoided, if possible." "The flaps are normally not used for increasing descent rate."

Thanks for the replies. All Gates and Limits were respected, and no aircraft limitations were busted, and I take on board what you are syaing about fatigue life BOAC.

Orbits on final are a very hot issue at the company who I work for after a few very spectacular cock ups. There are restrictions on doing orbits with the gear down and inside ten miles. I think from now on its more track miles for me. I know the aircraft can make it with less track miles, but it doesn't mean I have to!

- hmm! Your company is not alone:).

I would recommend a 'go' at para 2 of post #3 next time. Folk are SO reluctant to get energy DOWN for the 'expected' visual, and it really does not use much extra fuel/time if for any reason you then decide to take radar vectors etc. The slow speed/gear/approach flap will also save time in the long run if you are 'high' as you will use so many track miles and although it seems to take an age, as PantLoad says, it does not, in fact.

Like PL I caution against gear at high speed for the same reasons - plus the same fatigue issue, and I have a personal 'limit' of 230kts (737) for 'planned' gear extension - and try to make a quick PA beforehand if the situation permits, as it is so noisy and 'unexpected' for the pax (and crew:D)

I have been put off orbits a little after our incidents to be honest BOAC, and I certainly wouldn't want to be the guy who ends up in front of the CP for a "No tea, no biscuits, your hat my office, axminster shuffle type interview" after these new restrictions have been published!

Correcting Flight from above the Descent/Approach profile

The only lateral manoeuvring that is acceptable to regain the vertical approach profile is as follows:

• Request entry to a published intermediate holding fix in order to lose altitude
in a clearly defined and controlled manner to achieve the platform or step
altitude at the correct speed and aircraft configuration

• Request an "orbit" that should be executed as a racetrack pattern for stability which is subject to the following:

(1). Not less than 10nms remaining to touchdown
(2). Descent to not below the MSA or 3,000 ft whichever is higher
(3). Max Flap 10, with speedbrake if operationally necessary
(4). Met conditions VMC

• If a visual approach has been requested and approved by ATC that is not
straight in then consider extending the downwind or widening the base leg,
subject to other traffic

• If required conduct a full published Go Around to another approach

• It is not acceptable to join a visual circuit from an incomplete Go Around

If there is any doubt about the successful outcome of the approach a Go Around must be the prime consideration and is preferred over any other method.

This airline does not permit orbiting manoeuvres inside 10nms from touchdown or with landing Gear extended.

Well - that nails your options somewhat:). Just to be clear - I am NOT advocating any 'orbits', gear up or down. Just forward planning and use of low forward speeds to help you lose the height if you need. That was the only way I could fly the VOR approach onto R35 in Pristina with a high sector MSA. Nothing else allowed me to achieve the profile and worked out to be the most efficient too.

The technique is really applicable to your 'bullet point' #3 and avoids excessive extension.

If the met for your destination and your knowledge tells you that a visual might be expected, plan your decent for the visual! Is that too simple?
If you really need to get down then you can use the very simple formula of 1000feet/nm. plus two miles to spool up/stabilise at 500agl.
This ROD is achieved once the aircraft is fully configured at 40 Flaps and with the speed stabilised at Vref plus 5 but not more than 140kts. This figure is good for all B737s in still air. The trick is to act against your instincts and pull the nose to above the horizon, stop the decent and configure on the speed schedule, reduce to 140kts. and then, and only then, lower the nose and watch the result!
I have seen it done quite safely from 7500 with 10.5 track miles to run.

Telstar - there should be enough here to give you some ideas. Posts 3,5,8,10 and 11 all advocate another way/ways to 'approach' the problem. Why not try them? No orbits, no breaking company 'rules' and safe efficient flying:ok: Enjoy.

If you are VMC, there is little wrong with an "orbit". You have to be situationally aware. My compatriots in Germany regularly extended Flaps to 5 and kept the speed at 240 Kts. This seems like bad airmanship but it works a treat.

The speed brake and gear combo is way less effective on the -800W than say on the -300.

What was the BOAC incident?

Does Flap ware actually occur whislt operating within the Limitations?:confused:

There are really only two things to say about all of this:
1) The esteemed gentlemen in DUB / EMA who spend a lot of time writing the books, do not spend enough time going to all those lovely north Italian airports: TRN, VBS, TSF, TRS…:mad:
2) You could do, what I would obviously never do: fly speed 220, F5, speed brake out, while looking at the box showing you a flight angle of approx 5,6 deg, all this while quietly thinking about the fact that you can the change the 5,6 to close to double digits by lowering the gear...:suspect: pure karate flying

Boeing recommend you don't use flap as an extra speedbrake.

Funnily enough most companies repeat this advice in their ops manuals. This is to prevent damage to the flap tracks and other bits. A flap track failure at worst may prove uncontrollable.

So do you follow the advice of the manufacturer or your mate on the flight deck ? Seems like a no brainer to me. Use the flap as the manufacturer and your company recommend. To do otherwise is poor airmanship.

Exceptions would be situations requiring you to get on the ground asap. You then can use the full limits knowing that nothing will fall off.

As pilots we often complain when the company rosters us to the edge of legal limits. We observe that while it may be legal it is most certainly not wise over a protracted period as sooner or later there will be an unpleasant consequence. Why is the aircraft any different especially as when we make the rostering complaint we ofton observe that if we treated the aircraft the way the company treats us they would break.

I do work for a large loco in Europe so do know what the pressures are.

I have flown in Europe a few years ago but not sure where you are referring to. Northern Italy descending over the Alps?

Why not bring the speed back to min clean while you are being kept up then dump gear/use speed brake and accelerate back to 250kts when cleared to descend.

The flap 40 trick works well but I only use this closer in as it stuffs up traffic flow! I need speed about 155kts with flap 40 at higher weights on the 800W to achieve 1000'/nm.

Interesting thread so far .. two comments I would echo ..

(a) ... If you really need to get down then you can use the very simple formula of 1000feet/nm. plus two miles to spool up/stabilise at 500agl. .... I have seen it done quite safely from 7500 with 10.5 track miles to run.

Personally don't like full flap but approach flap with a bit of speed on works to give around 1/1. I routinely used this to effect DRW-CNS in westerlies .. approaching overhead the upwind end at around 10000 and then a dirty idle descent down to end downwind .. spin up ... landing flap and a normal base and final. Worked a treat and the pax didn't have their teeth rattled out of their heads with turbulence generated gyrations ..

(b) the limitations address the basic structural requirements and a presumed operational scenario for fatigue calculations. He who routinely pushes the gear and flap limit speeds goes outside the normal sort of fatigue presumptions and will experience a significant increase in routine maintenance costs for gear doors etc., and flap hardware. Probably not an accident concern if the routine maintenance is kept up to the mark as the hangar boys (most likely) will find the usual cracking long before things depart from the base structure. But it's a very silly operational and commercial practice. In the occasional emergency situation where you MUST get down .. the considerations are quite different. However, for routine operational use, the sums just don't add up.

- hence the reason for full flap, JT, to AVOID the "bit of speed on" for those very reasons.

Acknowledged but the operator had an SOP along the lines of full flap requiring to be spun up regardless of height so the approach flap was necessary to comply. Only looking at a modest speed delta .. not anywhere near limit speed for the setting.

In any case, provided that one monitored profile progress critically (and we were real good at doing mental arithmetic) there was never a problem with the final transition to landing configuration.

The way I see it as long as you stay under the limitations you are doing just fine. If they wanted you to fly slower with the flaps and gear out they would put it in your manual(s).

We are paid to fly airplanes not "play" structural engineer and guess/assume that we should operate below the limits. There is no reason to do a 360, especially when you need to get to the hotel bar for drinks.

The limitations are for normal operations, not emergency circumstances... If do don't agree show me where in your books it lists "Prefered Limitations, or Limitations for Normal Use." Untill a my company publishes "Recomended Speeds" that are lower than the current limitations I will use the limitations as my guide.

In an real emergency if I'm 20 knots fast and I want the gear down it's comming down 20 knots fast, same thing with the flaps.

ERJFO, I'd be intrigued to know what type you fly and who for as I find it hard to believe that neither your manufacturer or company do not publish advice on the matter. I'm assuming that you fly a commercial airliner.
Boeing Flight Crew Training Manual under Flap Usage sub heading Flap Maneuvering Speed Schedule.
"During Flap retraction/extension, selectingthe next flap setting should be initiated when reaching the maneuver speed for the existing flap position."
"The maneuver speed for the existing flap position is indicatd by the numbered flap maneuvering speed bugs."
Thats Boeings viewpoint, I would be amazed if Airbus and other manufacturers did not have a similar standpoint but I do not have the written word to quote on that.
My company SOP amends this slightly by advising that you select the next flap setting, during extension, when within 10 kts of the maneuvre speed for the existing one to avoid unecessary auto-throttle movement. Always assuming you are at a point when you want the net flap setting. We are also permitted to fly the usual ATC speeds when required by them which may be a bit above the maneuvre speed. Boeing elaborate to similar effect later in the FCTM.
I very much agree that we should not play structural engineer that is precisely why its important to know and follow the laid down guidance.
Take Flap 1 on a 737NG. The Maximum Operating Speed is 250 Kts but at Typical Weights clean speed is about 195 Kts. Thats a 55 Kt difference which at 1/2 MVsquared makes a hell of a difference to wear and tear on the flap.
During normal ops anyone trying to operate the flaps significantly outside that advice will be politely told not to with the reasons given at a suitable juncture.
So there you go Manual references, hope that helps

The limitations are for normal operations, not emergency circumstances

Actually, the limitations are for both ...

The basic structural, handling, performance etc., qualification of the aeroplane is based on limitations as these provide the fence around the paddock.

Fatigue and planned maintenance considerations are based on a presumption as to the way the aeroplane is going to be operated. If the aircraft routinely is operated less conservatively than such presumptions then one anticipates observing an increase in costs associated with routine maintenance activities. Indeed, if one considers structural fatigue, there has been a number of cases of wings falling off in flight as a consequence of this very point ...

One would be VERY wary about, and careful when, exceeding limitations during emergency procedures ... unless you definitely know that, by doing so, you don't create a bigger problem (generally you won't and can't know this) ... and, at the end of the day, the FDR etc., will catch you out at the enquiry ... be very prepared to defend yourself against some searching questions in respect of acts/omissions which might be indefensible at law.

My company/type doesn't provide flap selection guidance. If it was provided (like the guidance that exists for you) I would absolutly follow it.

John, in regards to following limitations in an emergancy... I urge to to look at USA FAR 121.557 part (a) states:

"In an emergency situation that requires immediate decision and action the pilot in command may take any action that he considers necessary under the circumstances. In such a case he may deviate from prescribed operations procedures and methods, weather minimums, and this chapter (FAR 121), to the extent required in the interests of safety. "

Based on my interpretation of that law it looks like violating limitations if needed to preserve saftey of flight is anything but indefensible. Infact the above law says the pilot in comand my deviate from the entire section of FAR 121 (all rules governing airline operations).

Loosly translated if you have to you can break every rule in the book to save lives. An example: If the airplane is on fire, I'll exceed a max tailwind and a max landing weight limit to get it on the ground. Remeber, first rule is to fly the airplane. Now to the same extent I'm not going to overspeed the flaps just because I've declared an emergency for somehting unrelated, like a break failure. Remember procedure is all well and good but sometimes (hopefully once in his carrer) the PIC has to earn his pay and make decisions when there isn't time to open the book. I.E. I'm not going to be the guy that dies because he's reading the evacuation checklist when the center fuel take explodes.

ERJFO, I'm truly amazed ....

Maybe it would be appropriate for either yourself or your company to clarify this point with the manufacturer of your type and to check the fatigue assumptions on the profiles you fly.

TTFN

We have maximum flap speeds and minimum manuvering speeds, but we aren't told when to select the flaps. Just not to overspeed them or fly slower than the minimum manuvering speed for the current flap setting.

ERJFO,

Guess that we will just have to continue to disagree. Suggest you consult a lawyer at some stage in respect of your regulatory interpretation ... you will/may still be called to justify your actions if you elect to operate outside the requirements .. and, if you can't do that to the satisfaction of the Regulator/Judge/etc (as opposed to your own satisfaction) then you are at some degree of risk ...

Wow!!! How this thread has evolved!!!
 

Well, I will be the first to admit that I am not a lawyer...especially one who specializes in aviation law...nor am I an administrative law judge, nor am I an FAA person, nor am I an NTSB person...

BUT,

The FAR 121 reg quoted above...and there's a Part 91 reg that is similar...is for emergency situations. AND, the NTSB, FAA, administrative law judge, etc. will expect that the pilot's actions (ostensibly as result of an emergency situation...and the declaration of an emergency) will have had to be something that was to directly aid in mitigating the situation.

I'm trying to think of a situation where exceeding the flap speeds would help in an emergency.

An example of a deliberate violation of a regulation is the exceeding of the 250 kt below 10,000 feet rule. You have some guy on board who is about to die of a heart attack, and you're hammering the speed to get the guy to airport "X" where the cardio medics are standing by.

This would be OK, but during the approach, you start hanging the flaps out at Vfe + 10....and that's not OK.

Again, I am NOT a lawyer, judge, FAA guy, or NTSB guy.

Again, I think they would look at your actions, your logic, and how all of this applied to the emergency situation. I really don't think they give you carte blanche....

Just my humble opinion. No disrespect intended to those who disagree. I could be, very well, totally wrong. (I am much of the time!!!:bored:)


PantLoad

John,

Thats fine with me. I'm just reading the rules from the book. I do have one question for you - Are you saying in absolutly no circumstance is it ever okay to violate a limitation or regulation? What is it exactly about my post you disagree with?

Emergencies are very different from ops normal. What I will say is that things will need to be getting rather extreme before you'll find me busting airframe limits. One thing is for sure, if it gets to that point you will be justifying your actions to people who will pore over the detail second by second and in minute detail. If its me and something like that has happened I'd just be glad to be alive.

ERJFO if your company does not publish the advice then I would suggest you use common sense. Push the limits plane breaks sooner, fly conservatively plane lasts longer. Simple stuff. On the other hand if you disagree why don't you drive YOUR car continuously at max revs, slam the brakes, power slide round corners etc being carefull to keep just inside the manufacturers limits. Of course that would be dum though wouldn't it as it would cost YOU money and most probably penalty points or your license. Treat your companies aircraft poorly and it will cost them money and by default you as well. To operate to the limits against common sense to me smacks of a certain degree of stubborness.

If your still struggling write to your manufacturer and ask their advice.

Yep!!!
 

Ashling,

You speak with great wisdom!!! Yep, the airplane is our jobs. The longer it lasts, the better off we are. The cheaper it operates, the better off we are.

I used to try to explain to the 'new guys' this way:

Our company manufactures widgets. We have a big plant, and in it are many widget machines. These machines are expensive to purchase, expensive to maintain, and finicky to operate.

And, the widgets, thenselves, sell for a price only pennies above the cost to produce. So, we have to crank out as many as possible in any given day. (Hence, good aircraft utilization with good load factors.)

It's important that we, the widget machine operators, treat the machine with kid gloves. We know better than anyone how to baby the machine, to make it last, to make it produce the most widgets in a work shift, in a machine's lifetime.

If we fill in all the above squares, the bean counters will be pleasantly surprised...and will happily replace the widget machine when its life has expired...and gladly train the operator on the new state-of-the-art widget machine that replaces the old one.

And, the bean counters will buy more widget machines...and cram them into the factory building, since these machines make a profit for the firm...and they'll hire and train new operators to operate these machines...and you'll gain seniority...and more pay and benefits...and vacation, etc., and job security.

So, it's important to save 30 seconds of flight time by going to the trouble of asking ATC for 'direct' or doing a slow-speed, thrust-idle descent...using your skill and experience to plan the descent so you don't touch the thrust until 1000 feet (500 feet VMC), working out the flaps at the prescribed speeds (since you so well planned the descent in the first place). And, you make a nice touchdown using the proper reverse and braking procedures to minimize brake wear.

You all get the idea...

Happy customers, minimal costs, keeping that widget machine going and going, because you baby it.

A result, job security, good pay, profitable business. Fast upgrades for the F/Os. (The bean counters purchase more widget machines.)

Or, the other side of the coin...If we had to, ourselves, pay for flap repair, brake replacement, fuel, etc., we'd operate a little differently.

The funny thing...we are paying for it, ourselves...just not directly and not obviously. But, we are paying for it.... Yep, we sure are!


PantLoad

7 to 8000 above profile? How far from the airfield? The best you will safely achieve ( stable rod and thrust at 1000' agl) in any boeing is double the profile at 10 nm flown with flaps 25 gear down on 737 170 and gear down flaps 20 on 747 classic and 744 160knots. You will get a rod of 1500 or so and visually will see the aimpoint well short of the threshold until you are in the 3 degree slot. So that means 3000 above profile at 10 nm and configured. An extra 10 track miles doesnt mean an extra 3000 feet unless you are similarly configured. Racing towards the ground at high speeds is a problem unless you have greater than a 6G rating on your aircraft. If ATC is the problem then time to make a phone call and have a cup of tea to mutually understand each other then work out somewhere to orbit or race track and descend. The fuel considerations are minimal as you burn 40 kg a minute in a low level pattern of 4 minutes equals 160 kg. You only burn 300 kg in a complete descent so an idle descending holding pattern or orbit costs zip. regards

... are you saying in absolutly no circumstance is it ever okay to violate a limitation or regulation? What is it exactly about my post you disagree with? ...

Peace, brother .. keep in mind

(a) this Forum has an educational thrust for the newer PPRuNe folk so those whose beards are greyer tend to emphasise the conservative

(b) regardless of your personal thoughts, the captain WILL be called on to account for his/her actions in the event of an incident or accident (presuming he/she survives the latter).

A colleague comes to mind whose experience following a fatal (in which he had no part) involved spending a day or two in the box with the wolves doing their best to attach blame to him and the company .. be VERY wary of thinking that the captain is some sort of holy (wo)man who can do his (her) own thing in isolation ...

(c) sure, the captain may do what is considered necessary in an emergency but consider (b) and the fact that the typical pilot has little knowledge of design, testing, and certification .. ie how "hard" is that limit which you are about to propose busting ... ?

John, thank you for your points... I understand your argument and tend to agree with what you said. Cheers!

Back to the original question. I follow all the macho arguments, and all the techno discussions. However, the original scenario was the crew are offerd a visual approach. That would suggest they can fly in whatever part of the sky they wish to achieve the meeting of a/c with gound at the correct place and speed.
It is said the company limitations are not allowing orbits on finals, within certain criteria. I know some of the N.Italian airfields concerned where there is often an unhelpful tailwind on a straight-in. However, what prevents a flight through the centreline and capture form the other side? This is not an orbit. Or, a turn away from the finals until at suitable height?
The drive & dive technique works, yes, but it has the pax hanging in their straps and the cabin crew hanging onto the trolleys as they career towards the sharp end.
The clearance was a visual approach, not an expedite landing. There's no fire or any other justification to exceed, limits or operate outside SOP's.
However, if ROD is what is required then gear (any significant drag) is best, but if you are pointing at a runway with gear out/speed brake and 245kts then, perhaps, you are in the wrong place. It is not a comfortable feeling, wondering if it is going to work out, or not. Hairs on back of neck etc.
If you are offered a visual in a small airfield, it might imply no other traffic. Why not consider a flight over the airfield into a visual circuit? Safe, smooth and comfortable.
The skillful pilot avoids getting into situations where he needs to use his skills to escape from them.