Jet Aircraft Handling During Approach & Landing
 

Hi,

It seems it’s difficult to handle (to reduce the speed and altitude) jet aircraft during approach and landing.

a) I am wondering if this occurs in all jet aircraft or only certain jet aircraft.

b) What are the causes of this problem besides approach idle (high idle)?

c) Which of two may cause more go-around: difficult handling of aircraft during approach/landing or complying with ATC requests? (If there is conflict between the two)

d) How often pilots perform a go-around?

Feedback appreciated

Regards

A good pilot understands his aircraft and the environment, and plans appropriately. If something unusual happens, then handle it the best way available.

Is this a joke? For a properly trained and appropriately experienced pilot, a jet aircraft is as easy to fly as a baby buggy is to push.

Planning and flying an approach in a jet is a lot like the approach to a woman, When you go down you slow down and the rest all falls into place.

On the other hand for the prop drivers when they go down they speed up hence all the confusion and rush and concerns of a missed approach.

:ok:

Plan plan and fly the plan

Simplistic replies
 

I think AeroTech had a good question. Quite often we read of airline accidents of overshoots and undershoots resulting in loss of life.
Basically, (and I am very basic :hmm: ) a newish light aircraft pilot can glide to a reasonably good spot landing. At night even with runway lights only they get a good sense of hight/flight path. So just where is the problem with you automated hot-shots? :oh:

ok, after we all agree that great pilots never fail :ugh: and the question therefore is obsolete......

so what is the problem with those jets on approach?
to me it seems that the problem is the dissipation of kinetic energy. ATC will sometimes not clear you for further descend for reasons like traffic or terrain. so your track miles decrease and your getting above your planned path
(so much for "plan ahead and fly your plan" :sad:)
you can shed energy by creating drag (flaps, speedbrakes, gear).
but you might be faced with quite ineffective speed brakes (eg B737NG), a very clean wing (eg B737NG) and company regs that don't allow flaps above 230 or 220 knots. and people are reluctant to drop the gear 30 miles out, because you might end up in a situation where you have to apply power again....

Jets are designed to have low drag - 'cos that's more efficient. This means they need time (i.e distance) to descend and slow down. Various events may conspire to mess up the plan - the secret is early recognition and prompt appropriate action.

I beg to disagree with your classification "of jets being difficult to handle during approach". As a matter of fact, ANY TASK is difficult if you don't know what you're doing.

The entire manual suite tells you how to fly the thing, and with PROPER training, anybody can do it WITHOUT AN INORDINATE AMOUNTOF DIFFICULTY.

The problem is when the pilot is knowledge-challenged (no matter how many hours he's got) and wasn't properly trained.

What's difficult with adding at least 7 miles to your usual distance=altitude x 3 for speed dissipation from 300kts? Fly the attitude approx 2-2.5 degrees with thrust equal to gross weight plus 5% as your final N1 on calm winds at Flap 30?

Random thoughts.
 

So if you all are comming down on AP and AT and your too high. The computers start trying to correct. Esp. with protection laws, are they more limited in pulling power off than a hand flown approach?
My few observations with airliners on approach is they seem to be dragging it in under a fair amount of power just to counter all the drag hanging out. Simple answers mates, or just ignore me.:O

One of the current problems is that some folks persist with the automatics when the computers clearly are not coping. No different to a Pawnee .. if it's not doing what you want it to do, make it do so .. can only be one boss of the board ...

Despite my usual abismal standard, going down and slowing down is a relatively simple affair (cos if I can do it..anyone can) as long as you understand the basic energy management requirements of your present mount.
Yes its all very well saying its 3 X etc etc, and then add a bit for wind/wife and kids/crap radar vectoring, but the reality is, you develop a feel and an understanding of how things should look.
I use the 3 X's table, but I also have a bit of a guess, then I re-guess, then guess some more.
My only hard and fast rule on the current beast (wingletted 757's and 767's) is gear down at 5.5 DME to achieve 160Kts at 4 miles.
Other than that, flying a jet is more like thinking 50 miles ahead...and in my case..behing 20 miles behind:ooh:
The only G/A's I have ever flown have all been self-inflicted...:ugh:

"The only G/A's" ect. Haughtney1 sir, I think the OP and myself are wondering (generally) just how you got into that position where you couldn't pull power or throw out something to get back on track, maybe from 3 to 1 mile out. SOP limitations perhaps?

Thanks John T. Just so, but I always liked to feel or "listen" to anything the a/c was trying to tell me, esp. if it had anything to do with gravity. :)

Just a few thoughts
 

With a bigger jet, the momentum (product of size{mass} and speed{velocity}) is higher and so is the inertia. So it'll be harder to stop a bigger jet compared to a comparatively smaller one. So heavier and bulkier the jet, the harder it is to decelerate.

Another fact is that jet engines cannot be played around with like a small piston aircraft. It takes more time for the power to spool up.

And pilots perform and a go around whenever they feel its necessary.:ugh:


KJ

Are Jets diffilcult to fly during Approach and Landing
 

As long as you keep your thinking ahead of the aircraft, it is not difficult to fly a Jet or a Piston engine aircraft.

If you get behind the speed of any aircraft, then you have a problem or two!

Tmb

Confusion
 

Thanks King Julian. Yet reading this forum I've rightly or wrongly got the impression some (unwanted) high rates of decent have been accomplished. :)
And by memory, some approaches are made at flight idle from TOD to "right in close". (Which surly makes it difficult to reduce power to increase decent.)

And that something like 30+ % power is used for a 3 deg. slope. ie allows for a reduction if necessary.

And one thread recently stressed that if go-around power was pre selected, immediate power and thrust would be available, but yes I saw the french go into the forrest.

Don't know what the head banging on go-arounds is for, the high approach questions are WHY some get too high in the first place.

In my business, mostly one way strips (no go-around possible), well you just got low on approach and made sure you stayed that way.

Are you all allowed to be a bit low on the glide slope, or is the problem only with those somehow above it closer in?

Or am I totally out of my depth? :O

Air tourer

In an large jet transport, going "a bit low on glide slope" is a great way to rip off the gear of an airplane with high "eye-towheel" height. It has happened many times, read the TC TSB report on the Fox Harbor write-off of a GLEX.

The correct answer is to be stabilized on a 3 degree glide, configured, with power at a appropriate setting, on speed and crossing the threshold at about 50 feet. Thinking ahead and planning the arrival to get to that point at about 1000 feet AGL is the only "trick" and it isn't hard, IF trained right and apply proper discipline to the task.

GF

In a swept wing jet aircraft when you are on final approach you are in the 'speed unstable' area at the back of the drag curve - whereby any loss in speed increases your induced drag further. This means that speed can bleed off very quickly if you're not careful... :uhoh:

In the go-around the general rule is that a jet aircraft relies more on the retraction of high-lift devices as a quicker response than the engines spooling up as this can take some time, in comparison to the more or less instantaneous response of a piston engine.

Piston engine aircraft approach apeeds are further along the drag curve and are in the flat speed stable area of the drag curve. Any minor reduction in airspeed shouldn't make a vast difference to handling etc. Thus, it may seem easier to land a piston than a jet. :ok:

Reminds me of many years ago on the 737-200. One of our first officers straight off Piper Chieftains was undergoing the 737 course at the Boeing Seattle flight simulator. The Boeing instructor was well known for his sarcastic heavy handed instructional technique and terrified some pilots doing the course.

Barry was the first name of the first officer being "trained" or brutalised by "Joe" the Boeing sim instructor. After a particularly harrowing session, Joe said to the first officer: "Barry - one thing is for sure and that is you will never kill yourself flying a 737. And do you know why? Because when that mother-f****er crashes you will so far behind that aircraft you will never catch up with it":ok:.

is a great way to rip off the gear of an airplane with high "eye-towheel" height

as many of us with glider towing experience can attest ... much the same problem as the attrition rate of towline end rings on the top wire of the airfield boundary fence.

[As an aside, if folk are wondering why I haven't edited the profanity in Centaurus' post, it is one of the rare occasions where it should stay both due to Joe's persona (as cited in numerous other threads) and the pertinent relevance to the anecdote].

Hi,

Thank you for your feedbacks.

Regards

Aerotech,

What I believe other contributors are trying to say is that landing a Jet aircraft is not 'hard' providing you have been trained correctly, are a professional aviator (unlike some on their forum who seem to believe that a G/A should never be necessary) and are prepared and thinking ahead of the aircraft.

In response to your question though, flying a jet aircraft on approach does present a unique set of challenges. The list and intimate detail is far too exhaustive to discuss in full on this forum, however there is some excellent material published on it including 'Handling the big Jets' by J.P Davies. I have outlined a few points below.

Turbine vs Piston engine response: A piston engine aircraft has an almost instantaneous response to throttle adjustments, this is not true in jet powered aircraft. In Jets particularly at lower power settings it can take a significant time to 'spool up' This is why Jet aircraft operators require the aircraft to be under a stabilised thrust setting by a particular stage of the approach. Modern jet engine response time is however much faster than the engines of the past.

Jet Aircraft vs Prop aircraft: To make matters worse, when getting slow in a prop aircraft advancing the throttle immediately provides an increase in thrust and a very beneficial increase in propellor slip stream increasing lift over the wing, this is not true in Jets. Also, at idle throttle in a prop aircraft the prop generates a heap of drag allowing the aircraft to slow down very quickly (this includes turbo-props), in Jets at flight-idle the engines are still producing some residual forward thrust, this can make the aircraft very hard to slow down if the descent is not properly planned or the pilot allows ATC to subvert his/her plan.

Wing design: Modern jet aircraft Laminar flow and supercritical wings have a flatter Drag curve than traditional light aircraft. This has two effects. Firstly, the speed for minimum drag is higher (approx. 1.4 Vs1g according to JP Davies for a typical wing if memory serves me correctly, as opposed to 1.3vs in light aircraft). Going below this speed puts the aircraft on the back of the drag curve or 'speed unstable region'. Secondly, it is possible to miss this speed unstable event on a modern transport category wing, thereby allowing the situation to become worse (whereas in a light aircraft it is VERY noticeable), couple this with slow spool up times and no prop slip stream and it is easy to see why when flying a jet and getting slow it is extremely important to be positive with the thrust levers. Further study on wing design would encounter the subject of supercritical wings and the associated handling pitfalls with a low wing loading.

In summary, whilst not difficult, there are unique challenges to flying a jet transport cat aircraft. If the descent is not appropriately planned and managed or you encounter/allow something grossly outside of the plan (increased t/w, change of rwy, less track miles) it is necessary to immediately adjust the profile (speed control / track miles / speed brakes / config) If the adjustment required is too large and too late a G/A may be the safest/required option (Jet operators have strict stable approach criteria), doesn't happen often but does happen.

Sorry about the rushed reply but hope this answers some of your question. Highly recommend getting your hands on JP Davies book.

Regards,
MHA