Four whites on PAPI: Go around?
 

Hi, I've been wondering if given the following situation, a pilot should start a go around or not. Let's go:

While on a NPA, after coming out of the clouds, stabilized in speed and configuration, you clearly see the runway and the PAPI indicator, the only problem is, you see four white lights on the PAPI (too high), while keeping 1000 fpm (no more) trying to capture a normal profile towards the runway, based on the PAPI indication. While in this condition, you determine that touchdown will be made on the TDZ.

What do you do? Let's put asside the "my company SOP's say that we should go around" responses, that makes the decision easy, and what I'm trying to know is if there's a technical reason for a go around in that kind of situation, or a technical reason for NOT going around.

Thanks.

I suspect most would go around in accordance with SOP. Leaving that aside for a moment for the sake of the discussion as you ask, you do not specify the altitude at which you are breaking cloud/becoming visual, or the aircraft type/type of operation of your scenario. My point being that I'd suggest that there's a difference between breaking at minimums on a foul day in -for example- a medium jet at max landing-weight, i.e. go-around without hesitation, and, say, a light turpoprop/piston becoming visual at 3000 AGL at a ref of 90, which could arguably be made to fit the profile safely and with room to spare without the undesired unstabilised approach below 500/1000 (VMC/IMC).

Put a little thought in what you do. Are you at 3,000 ft or 1,ooo ft. At 3,000 ft you have options, at 1,ooo you have few. That is why you are the captain, you decided what to do.

Let's say you break off clouds at 2000' AFE, that's when you see the runway and the PAPI and although you are high on the approach, your assessment of the situation tells you that the landing can be made on the TDZ, and in fact, you do, despite having four white lights on the PAPI. You have four white lights until touchdown.

The aircraft can be a B737 or A320, doesn't matter, something in those lines.

Another case: There's a certain airport (real life) that if you follow the PAPI lights, you overfly the threshold at 100' RA. Some pilots say that you should try to have 3 reds and 1 white in order to overfly the threshold at 50' aprox. Others say that you should follow the PAPI light no matter what. There's nothing about this in our SOP's, so that's why I have this question.

Regards.

1. Just land.

2. What are you flying? MEHT. Ask 'em about that.

What would you do if there weren't any papi's?

What's the angle of the NPA and the angle of the papis from your approach plate as they don't always coincide. If you were on profile on the approach then your still on profile. Its not always a great idea to dive for the papis at low level. If your thrust is set and the aircraft is stable and heading for the touchdown zone then why change things to bring the papis inline when you weren't flying a visual in the first place.

Another question from a pilot with little real experience flying planes instead of books.

AlphaFloor

Make it right and land. If you can achieve a reasonable glide path (3 degrees + or - a little), near speed, descent rate < 1000 fpm, and cross the fence at 50'-70', you're golden.

The PAPI and the approach angles coincide, 3 degrees. You are definitely high on the approach, both "visually" and according to the PAPI indication, but with a 1000 fpm ROD, you estimate that a touchdown on the TDZ can be made, keeping all others parameters within the stabilized approach concept. In those conditions, you cross the THR at 100', but the touchdown is done within the TDZ, maybe in the final section of it, but still within the TDZ.

What airplane? How long a runway? How much excess runway do you have over calculated stopping distance?

If you want answers to YOUR question, it helps to complete the scenario by answering the questions of those who might provide the answers.

'4 whites on the PAPI' don't give a complete scenario. 'I'll land at the end of the touchdown zone' doesn't give much more...

Intruder is quite correct. Breaking out to a icy runway, high and maybe fast, just making the touchdown zone isn't good enough. Break cloud 1200 AGL to a wet runway, probably can make a correction to be "on profile" comfortably. Break out, high and fast at 200' with fog, going around would be a good idea, shouldn't have let it happen. Are you near max landing weight?

This is where experience comes in and should be earned before sitting in a RPT jet transport.

So far from the answers, I take there's nothing definite on this matter, it just depends on the situation, given SOP's don't say you should go around. That's what I wanted to know.

Wouldn't help to get into too much detail of a particular situation, just wanted to get a general consensus regarding this subject.

Cheers.

As 737Jock wrote,what would you do?
The PAPIS are only one of the available visual aids to maintain a steady profile to touchdown,the angle can vary as long as you maintain stabilised criteria such as rate of descent,touchdown point (within touchdown zone and within the landing diatance you calculated to be a safe touch down distance for the runway lengh and conditions.
I remember my first lesson on papis:
"4 whites:wake up!,4 reds youre about dead!":eek:

In between,it varies with calibration of the papis,some are design for high flight deck such as 747 and a B 737 will see 3 reds 1 white to maintain 3 deg and 1000 feet touchdown aiming point..

So 4 whites is a reference,a visual aid and not a factor for systematically having to go around,but remember,the closer you get in,the least margin you have,so it may be prudent to go around if by 500 ft you are not where you wish or recommended to be in your profile.

Say if something happens, a hard landing for example, the whole world will fault you for continuing despite the runway being long, wide... etc, with all factors considered; and the SOPs saying you should go around. They'll point the finger at you, always.

As ever the devil is in the detail, most SOPs require a stabilised approach, and they define the criteria. I would suggest that if at 500' AFE, (in VMC) you are still looking at 4 whites then Go-Around.

There is two concepts to consider, here:

1st, the concept of being able to land. You will go around at MDA if you don't have the required visual cues or if you have them but you cannot make a safe landing. In the situation you describe, you can make a safe landing, it seems..
but...

2nd, the concept of stabilized approach. In IMC, as per ICAO PANS OPS and most regulations, you have to be stabilized by 1,000 ft in IMC. In VMC 500. In this case I assume IMC, so if you happen to come out of clouds near minimums and you have 4 whites, you seem kind of unstabilized, because as you say, you are keeping a high rate of descent and you are still "capturing" the 3º slope. Therefore a Go around is required.

Landing in the TDZ does not mean anything in itself.
If you have a 2000 meter rwy and you land in the last bit of the TDZ, you only have 1100 meters left.
The manufacturer's FCOM data on actual landing distance assumes you land 300 meters after the threshold. So before the blocks. Go figure...
Too many variables to give a definite answer.
Go around is always a safe option when in doubt.

Judgment call. It's what you get paid for.

That approach is a shambles, and you should go around.

Are you sure about that? They may not specifically say that you should go around if the PAPIs show 4 whites, but that approach you describe is not stable.

The important thing is how you rectify the situation.

On no account with a modern slippy jet should you stuff the nose down.

Contain the speed first, get all the drag out (if it's not already there) and be ready to anticipate regaining the G/S with the correct approach power. (This is better done with manual throttle so apologies if that is not part of your personal SOP)

On the B757/767 sim it is possible to demonstrate that you can cross the OM (typically 4 miles out) 800' high with 20 flap and no wheels and, by promptly following the above technique, be in the slot by 500'.

And what if the papi's are at 2.5 degrees? For instance LIBR rwy 31. Normal approach path is 3 degrees, so if you follow that normal path the PAPI will indicate high.

I did once, as per SOP. Got a call from the FSO the next day wondering why we went around as he couldn't see anything wrong!

The best aviation answer is, "it depends.......".

The only thing truer than that is "it must have failed airborne boss";)

What height AAL is the visual reference acquired?
What is the groundspeed?
What kind of aircraft?

If you're high enough, an increase in RoD to capture the appropriate profile might be possible, followed by a reduction rather than keeping it the same all the way to the ground.

If the GS is 120kts, at 1,000fpm you're not far off a 5deg GS - not what most would call stable, unless it's an approach into LCY. At 160kts, it's just over 3.5degs, on the edge of one red three whites territory.

A turboprop with rapid response to power demands and plenty of drag when the power is taken off is very different to a slippery jet with high-bypass engines. Also, the potential is there for a) a heavy landing, due to the high RoD and low power/lack of response or b) landing deep due overcompensating and flaring too high.

Either way, you're adding risk at a critical stage of flight. As a 'heavy' driver, if I had already passed the point at which stable approached criteria were assessed and maintained, in IMC, then became visual with four whites, I would go-around.

How much fuel you got? In these days of minimum fuel departure, arriving with RESV +100 is not uncommon. Long RWY, Mk.1 eyeball and ROD<1000fpm, safer to land than join the queue and start screaming "fuel!"

Surely one of two things has happened here. 1 - you never got the aircraft established on the published vertical profile, in which case it the approach has not gone to plan and I would be very much go around minded. 2 - assuming PAPIs and instrument profile are the same angle then it sounds like a QNH blunder error. In this case go around check the QNH and start again.


In both cases if the cloud break is early enough then maybe it could be rescued but the aim must surely be to stabilise on the correct profile and not fly 4 whites all the way down. I don't see how anyone could consider that a stabilised approach.

I disagree with the assertions of a non-stabilized approach. Once more, we do not have enough information to make that judgement.

For example, on a visual approach at a steady 1000 fpm descent, this could be a perfectly "stable" and acceptable approach. If the runway is long enough, a safe landing could be made. Even if on an ILS, if the "4 white" PAPI equated to less than a half-dot deviation above the G/S, the approach could be considered stable, and a safe landing could be made after continuing at the 1000 fpm descent rate. As noted by a few above, there are airports where a 1000 fpm descent on short final is routine.

Still, I would not question anyone if he decided to go around in the situation. As for Lord Spandex Masher's FSO, he needs a different job if he is questioning a pilot's decision to go around ANY time!

According to my previous company SOP, as long as a touch down can be assure in the touch down zone the approach and landing can be continued.

And also depends in what altitude you are talking about.
According to Airbus FCOM 3. Procedures a 1 DOT deviation at 50 ft AGL is equivalent to 7 ft path deviation...

Unfortunately this is where we are now - no experience and therefore the need for our cadet pilots to have a totally black and white SOP in order to function - a complete, all encompassing, concrete SOP ...... that takes into consideration the 4+ million variations to the scenario.

If this continues the SOP book is going to get pretty thick.

He wasn't questioning my decision he wanted to know why we had made the decision as it wasn't obvious from the traces why we had gone around.

Just goes to show what you can get away with as far as FDM goes:ok:

Call visual.

Yes I accept that from a legal point of view, calling visual is a way out of that situation. However, think of any subsequent inquiry, should this approach not end well. You would be accused tunnel vision or push on itis. With or without SOPs we have to draw somewhere. I believe it prudent to draw that line well within the limitations of what I, or the aircraft can do. On occasion you may find it neccessary to operate to those limit, and possibly through no fault of your own (eg on board emergency).

To be fair, everyone is posting based on their own interpretation of just how out of shape this approach is. There is plenty of information left to the imagination here. But if 1000' fpm will just maintain 4 whites all the way down, then touchdown is at best going to be at the far end of the touchdown zone. Sounds ugly to me.


A colleague of mine told me his previous company was once very proud of the low number of go arounds they had. Once they implemented OFDM and saw why that was they weren't quite so proud.

1. The PAPI angle may be different to the approach angle I.e. 3.5 degree approach with 3 degree PAPI. Once you've gone around for one of these on an NPA with cloud close to minimums it hits home.

2. Your ops manual should stipulate stability criteria. On the A320 in easy we are considered unstable below 500 if VS is greater than 1000 FPM on a 3 degree +/- 150 FPM per half degree change in glide path. So if on a 3 degree you need more than 1000 FPM below 500 for anything other than transient stability then you need to go around.

3. The PAPI is calibrated for different aircraft - An A320 being Cat C. In NCE on runway 04L the PAPI are calibrated for CAT D aircraft. The amount of times I see my colleague religiously stick to 2 reds 2 whites when it isn't necessarily appropriate I've lost count on.

4. Below 200' the only thing that matters is the aim point. Completely ignore the glide slope and the PAPI. In my opinion your colleague calling 'glideslope' or '3/4 whites' inside the last 200' will be why there inexperienced colleague does a hard landing.

One of the biggest problems I see here is current CRM training and F/O's (PM) 'advocating their position'. So here you are <500', stable with <1000fpm and going to impact within an acceptable area of the rwy, considering its length, winds, BA etc. However, you have a shiny newbie as PM: they're screaming their heads off to "Go Around" because they see 4W. They've been trained, even brain washed, into forcing the issue. You've come off an NPA, you are at reserve fuel, there's nothing unsafe about continuing using your years of experience ands sound judgement: it's a bit late in the day to be having a discussion about it, but it could end up nasty, especially if the PM decides to tell tales even if the OFDM doesn't. Is this really increasing safety? It is sad that the few hot heads in LHS have caused the many to be tarred with the same brush.

R5, I agree. The airlines have simplified things so anybody can do SOPs without screwing up. I left right before this happened but 10 years ago we knew what was safe and what wasn't. Now if you violate SOP's you get busted so decide if you want to go around and land min fuel or get busted doing what we did for decades. My retirement flight they wouldn't clear me for the approach because they were saturated so I did the illegal high dive to intercept the glide slope that can't be done now. If I had gone around as required now I would have conflicted with departing aircraft on a runway 90 degrees to us but would have had no choice.

Wow, what was your FO doing?

You say you did an illegal high dive (what are they then Tom Daley?) on an approach that you weren't cleared for in, obviously, busy airspace because ATC was saturated and you were the most important and you think that's good?

By the way, as you appear to be out of date, you do not get "busted" for violating SOPs.

Wow… so often on PPRuNe people try to interpret people wrong.. just so they can throw some !!!!.

How about: late approach clearance, now above G/S, having to do a little "dirty" dive to save the approach. Still well within common sense.

How about -
Sounds to me like he wasn't cleared for an approach so just did it anyway, illegally.

That I can live with but is it illegal? No, didn't think so.

Of course, I wouldn't have to try and interpret things if people were clear what they meant in the first place.