A question from pilot to controllers

[Rob Barton 1216141]

Hello all,

 

Small question for you.

 

If a pilot is given clearance to line up and wait, should the pilot taxi and hold to the runway threshold seeing as the runway in question has a displaced threshold?

 

I've checked EASA regs and it seems to be the case but I got told off last night by a controller for doing so as he thought I was taking off.

 

Thanks in advance for your help.

 

Rob

[Simon Kelsey]

The three most useless things in aviation: altitude above you, fuel on the bowser and runway behind you

 

The short answer is no (be interested in that EASA reference though!) - just enter the runway and line up where you are. Remember the displaced threshold is for landing - the area prior to the displaced threshold can and should be used for takeoff, [Mod - Happy Thoughts]uming it's not marked otherwise.

 

To think about it another way - if you were lining up at an intersection beyond the threshold, would you taxi back along the runway to the threshold if you hadn't been explicitly cleared to do so?

[Rob Barton 1216141]

Noted and thanks very much for clearing that up.

 

Rob

[Andreas Fuchs]

Hi Rob,

 

Simon already gave you the answer that is valid in 99% of cases. I would like to add that during low visibility conditions/operations pilots are to identify the runway by seeing its markings (numbers). For doing so, it will be necessary to slowly taxi forward to the displaced threshold and then wait there, when you can read the runway identifier.

[Rob Barton 1216141]

Thanks, Andreas

 

Rob

[Mats Edvin Aaro]

Depends, there are different versions of displaced thresholds.

 

First off, you have permanently displaced threshold (the most common one), which is marked with centered white arrows before a line of small arrows and a thick solid white line, which marks the start of the runway (threshold). This is available for taxi and takeoff, but not for landing.

 

Then you have the blastpad/stopway area (officially called Pre Threshold Marking Area) which is marked with something called chevrons. They are yellow arrows which span on the width of the runway. This is not authorized for aircraft movement, and is in some airports used as a stopway (sometimes equipped with an arrestor bed). These exist when the paved area of a runway not suitable for aircraft movement exceed 60m.

 

You also have different variations of these as well as others (permanent vs. temporary displacements, taxiways etc).

 

And for those nerds out there: http://ww1.jeppesen.com/docomeents/aviation/business/ifr-paper-services/airport-signs.pdf

[Andreas Fuchs]

Hi Mats,

 

no, you are missing the point. Under low visibility conditions ("LVP in force") it may be necessary to positively identify the runway and the only way is to read the numbers/identifiers. In my company it is therefore mandatory to taxi to the displaced threshold to read the identifier, this is not optional.

[Mats Edvin Aaro]

I'm a little confused as to which part of my post you considered wrong Andreas.. Can you elaborate?

 

I can't see where LVP conditions come into effect here?

[Andreas Fuchs]

Hi Mats,

 

you wrote

Depends, there are different versions of displaced thresholds.

while my point is: it does not depend on this. In LowVis I always have to taxi forward to the threshold, no matter whether I could legally use the runway ahead of the displaced threshold or not.

 

Maybe I misunderstood your post?

[Martin Loxbo]

Seems to me like an odd way of wasting usable runway! What if you're performance limited so you need the full length? You can't use that runway in LVPs then?

[Andreas Fuchs]

That never happens, our business jets get airborne within a few feet. It is our law that we identify the runway and also [Mod - Happy Thoughts]ess the RVR ourselves by counting lights. The correct distance between centerline lights may also only be available from the original threshold. There are a few reasons and above it all "it's like this".

[Dhruv Kalra]

That never happens, our business jets get airborne within a few feet. It is our law that we identify the runway and also [Mod - Happy Thoughts]ess the RVR ourselves by counting lights. The correct distance between centerline lights may also only be available from the original threshold. There are a few reasons and above it all "it's like this".

If you’re waiting until you’re actually on the runway to positively identify that you’ve lined up on the correct surface, you’re likely too late.

 

There are countless runway identification markings prior to the hold short line, including surface painted hold short numbers and runway identification signs adjacent. I’m with Martin above - it seems counter-productive to waste usable runway which is factored into your takeoff and climb gradient performance calculations.

Edited November 28, 2018 at 04:40 AM by Guest

[Andreas Fuchs]

Hey Dhruv,

 

I am doing this for a living, I think I know what I am talking about. Our operations manual is dictating that we follow this procedure.

 

When you have a runway that is 7,000ft or 10,000ft long and your plane needs 3,000ft takeoff distance (=start of takeoff roll until reaching 50ft above runway), then it does not matter if you are missing out 1,000ft or runway. This is - of course - factored into the t/o and climb performance.

[Dhruv Kalra]

Hey Dhruv,

 

I am doing this for a living, I think I know what I am talking about. Our operations manual is dictating that we follow this procedure.

 

When you have a runway that is 7,000ft or 10,000ft long and your plane needs 3,000ft takeoff distance (=start of takeoff roll until reaching 50ft above runway), then it does not matter if you are missing out 1,000ft or runway. This is - of course - factored into the t/o and climb performance.

I did it for a living for 3500-odd flight hours, and now I'm a controller. I think I know what I'm talking about, too.

 

It may be different on your side of the Atlantic, but I guarantee that if you start a taxi down a runway to get to the end of the displaced threshold at a place like 31L at JFK (where the threshold is displaced 3200-odd feet) after being given LUAW, you're going to alarm the ASDE-X safety logic and give a local controller a heart attack. Also, what happens if you're issued an intersection departure and can't read the numbers since they're behind you?

[Andreas Fuchs]

Simple: I will not accept that intersection, because I can't. Obviously, in JFK, I'd request intersection K or KD to avoid the scenario that you described. Aviation is not black&white, there are many different shades of grey. But hey, I will be in the SIM in January and I will take this up to our instructors.

[Mats Edvin Aaro]

In LowVis I always have to taxi forward to the threshold

 

Aah, I think you did. Of course there might be other procedures in LVP, but I didn't mention LVP anywhere. My point was that whether or not you need to taxi forward to the threshold Depends on the type of displaced threshold, i.e. runway markings… But i see what you mean!

[Andreas Fuchs]

All good

 

I just called my flight training manager and he will talk to his examiners to find out about these Low Vis Procedures. I suspect that the main reason is not the runway identifier itself, but the spacing between the centerline lights. If we cannot be sure what the distance between them is, we cannot [Mod - Happy Thoughts]ess the current RVR.

[Magnus Meese]

Counting lights? Is that common? Are IRVRs that unreliable? I mean, there's a reason they've mostly replaced human obs, right? Also, are there no countries that file differences to ICAO specs on spacing of lights, and if so, do you keep track of all these differences?

 

APS pleb here, confused as always with things on the surface.

[Simon Kelsey]

Counting lights? Is that common? Are IRVRs that unreliable? I mean, there's a reason they've mostly replaced human obs, right? Also, are there no countries that file differences to ICAO specs on spacing of lights, and if so, do you keep track of all these differences?

 

APS pleb here, confused as always with things on the surface.

 

Andreas will be able to answer in more depth, but in short a 90m visual segment is always required at the start of the takeoff run (6 lights at 15m spacing).

 

It is also permissible in some circomestances (down to 150m RVR) to replace the reported value (or if the RVR is not reported) with pilot [Mod - Happy Thoughts]essment (i.e. up to 10 lights, depending on the cockpit cutoff angle etc).

 

The actual runway centreline light spacing is shown on the charts (and I think is ICAO standard for a CAT III runway in any case).

[Andreas Fuchs]

Simon's spot on! I got nothing to add.

[Magnus Meese]

Thanks for the reply. I'm not really confused on runway lighting and strip stuff, I'm kind of sort of required to know that stuff anyway, though I don't apply it working radar.

 

My confusion is as to whether counting lights is commonplace, when most III-runways have two or three IRVRs that provide that information for you, and the tower guy/gal provides that information. Also, are there countries which have filed differences from ICAO on RW lighting, and do airlines/flight crews keep on top of that if this is the case? I know for sure countries do all kinds of stuff with taxiway lighting, so I would [Mod - Happy Thoughts]ume some could be inventive enough to mess about with runways as well.

[Simon Kelsey]

My confusion is as to whether counting lights is commonplace, when most III-runways have two or three IRVRs that provide that information for you, and the tower guy/gal provides that information.

 

Yes - because the purpose of counting the lights is to ensure that there is a 90m visible segment in front of the aircraft (bearing in mind that the cockpit cutoff angle will mean that there is an area in front of the aircraft which is included in the RVR reading but is not visible from the flight deck), and/or to replace the measured RVR value with pilot [Mod - Happy Thoughts]essment if need be (so if the reported RVR is less than the 150m required but on lining up you can count 10 lights (allowing for the cutoff angle) and have a 90m visual segment as well then the reported RVR may be disregarded).

 

Also, are there countries which have filed differences from ICAO on RW lighting, and do airlines/flight crews keep on top of that if this is the case? I know for sure countries do all kinds of stuff with taxiway lighting, so I would [Mod - Happy Thoughts]ume some could be inventive enough to mess about with runways as well.

 

I'm sure there are but, as I say, the runway light spacing and type for a specific runway is provided on the charts for that airfield, so provided the crew have an up to date chart then they will know the spacing...

 

Is that what you were asking?

[Magnus Meese]

Mostly, thanks. I just had never registered the counting of lights as a procedure when IRVR is installed and operational, be it on the jumpseat in LVP, cockpit video, or just any old docomeent, and thus curious to as if everyone does it considering I've not noticed it in either of those first two situations. If everyone does count them, are some/all companies doing this silently?

[Andreas Fuchs]

I have no idea whether all companies do it, or not. We (NJE) certainly do it and we train it each and every time we go to the SIM.

[Rob Nabieszko]

As another RW pilot, yes we count lights for any RVOP or LVOP departure. This is true of 2 different companies I have worked at and would be considered a failure in the sim if you did not.

 

While RVR is a useful information tool, it is not located on the runway, where the visibility matters. Although unlikely, there could be variations from the runway to where the RVR equipment is located.

 

In Canada, the regulations state specifically that the Captain must be satisfied that the required visibility is available. Counting lights is the most reliable method on the actual runway.

 

As far as the original question, there is no legal requirement to taxi to a displaced threshold, though specific companies may make it a requirement.

 

As a controller, I would have no problem with someone using the displaced threshold, provided they COMMUNICATE this in advance. The normal expectation would be to line up at the point where you enter the runway (within 100-200 feet). I would also get very worried that someone taxiing 1000 feet or more down the runway is taking off without clearance, or could even collide with traffic crossing downfield.