Question about "line up" and holding on the runway, before takeoff clearance is given

[Richard Lee]

Hi. For all the times I have used VATSIM (I am still relatively new to VATSIM, I have probably flown around 8 to 10 times total), I have always been given the clearance to enter the runway and takeoff, before the runway holding position marking.  While waiting at the holding position marking, the next instruction I have received from a VATSIM controller is that I am cleared to enter the runway and I am cleared for takeoff.  I have never been instructed to "line up" and hold on the runway, and wait for another instruction to takeoff.  But maybe this is because all the airports I was on in VATSIM, are usually not that busy, or I avoid flying during busy hours, and/or I avoid an airport if there is an event there.

Anyways, I was watching a someone stream a flight on VATSIM today, and the airport was pretty busy.  The pilot on the stream was given instructions to "line up," and this was the first time I had heard of such an instruction.  I got into a conversation with someone in the chat on the stream who is a VATSIM veteran, and that person was nice enough to tell me some variations of "line up." Now, I have more questions about how "line up" is used.  For clarity, I will use this diagram as the reference, when I ask my questions about "line up."  Here are the two uses of "line up" that person in the stream chat gave me:

1. "N978CP, via (holding point) line up runway 15"

Using the diagram above, if we substitute A15 as the holding point, I guess the instruction would be  "N978CP, via A15, line up runway 15."  If I am waiting at holding point A15, does this mean that I can cross the holding position marking at A15, and enter runway 15, and wait at the end of the runway for ATC to give me clearance to take off?

2. "Behind the departing Southwest 737, via A15 line up runway 15 behind"

Ok, the person in chat told me a conditional can be used.  This instruction doesn't make sense to me at all. I am guessing this mean Southwest 737 is already on the runway and is currently taking off, and ATC is asking me to enter the runway and "line up" and wait for clearance for takeoff?  But I'd rather not guess.  If somebody can explain what this means, that would be appreciated.

Thanks for your help in advance!

Edited July 29, 2022 at 03:00 PM by Richard Lee

[Alex Ying]

The phraseology examples you indicated above sound like they come from Europe, but since you linked an FAA diagram, I'll answer for the US and FAA-land.

1. FAA phraseology is "[Callsign], runway [Runway] ('at [intersection]' if necessary), line up and wait." When you get such an instruction, you do exactly what it sounds like you're being instructed to do. You cross the hold short line and line up on the runway in the correct direction, then wait for further instructions. Examples:
   • "AAL123, runway 15, line up and wait." (if you were at the end of the runway)
   • "UAL123, runway 15 at B, line up and wait." (if you were waiting at intersection B)
2. In the US, you will never get a conditional line up and wait instruction, it's not allowed in the US. You may sometimes get a line up and wait instruction while the previous departing aircraft has just been cleared for takeoff and you're entering the runway from behind them (same taxiway or taxiway further back), so they are on the runway about to begin their takeoff roll. This is not a conditional instruction since you are expected to execute it immediately. You're not waiting for something to happen, you should immediately cross the hold bars and line up on the runway and wait for further instructions. Example:
   • You (DAL123) are short of the runway on A. SWA123 is lined up on the runway waiting for instructions.
     "SWA123, runway 15 cleared for takeoff"
     "Cleared for takeoff, SWA123"
     "DAL123, runway 15, line up and wait"
     "Runway 15, line up and wait, DAL123" You are expected to line up on runway 15, even if SWA is still on the runway. You would only get this instruction if you're already behind SWA.
3. You will never get a LUAW instruction while an aircraft has been cleared to land on the same runway, but you may get a LUAW instruction with an aircraft on approach but not yet cleared to land. That would sound like this:
   • "JBU123, runway 15, line up and wait, traffic on a 3 mile final." You should immediately start moving across the hold bars and line up on the runway since the controller is trying to get you out before the next plane lands. You should expect a takeoff clearance pretty soon since the traffic is only about 1-1.5 minutes out from the runway. You would probably also hear the controller issue a landing clearance to the traffic behind you, but only after you've been cleared for takeoff

Edited July 29, 2022 at 03:45 PM by Alex Ying

[Don Desfosse]

Richard, thanks for asking.  Line Up and Wait (LUAW) operations are indeed beneficial when it's busy.  They help maximize runway efficiency by allowing an aircraft to get onto the runway and be fully ready for takeoff just as soon as it is safe to do so (e.g. ensuring wake turbulence separation from a previous departure, ensuring an arrival is safely clear of the departing traffic, etc.).

I'll preface my reply by saying that based on the example aircraft you used above (which I've actually flown RW BTW 🙂 ), plus that the diagram you referenced came from the US AIM, I'm assuming your questions pertain to operations in the US, and thus my answers will be appropriate to the US.  Though the intent will be same/similar across the globe, different countries will have different phraseology and different rules (e.g. conditional clearances).

The terminology you mentioned in your post isn't quite correct for US procedures, and I would not expect a conditional clearance in the US (e.g. "Behind the departing Southwest 737, line up and wait.).

Some references include:
US AIM section 5-2-5 (https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap5_section_2.html) (what pilots usually reference)
US FAA JO 7110.5 section 3-9-4 (https://www.faa.gov/air_traffic/publications/atpubs/atc_html/chap3_section_9.html) (what controllers are regulated by)

In your examples:

1a:  I would not expect to hear anything about holding point A15, as A15 is at the end of the runway (again, this is applicable to the US, and is different in other countries).  In the US, it would simply be, "N978CP, Runway 15, Line Up and Wait."  If you were departing Runway 15 from the intersection of B taxiway, it would be, N978CP, Runway 15 at Intersection Bravo, Line Up and Wait."

1b.  After given a LUAW clearance, yes, you would cross the holding position marking at A15 and enter runway 15, stop on the runway, and wait for ATC to give me clearance to take off.

2a. In the US, you cannot be given a conditional clearance along with LUAW (but you can in most or all of the rest of the world).

2b. Yes, you would make sure you didn't hit or get blown over by the departing aircraft, and then line up and wait as discussed above.

 

Hope this helps!

 

[Andreas Fuchs]

Outside the US, you will come across conditional clearances every now and then. In some places ATC will ask you first whether you got the traffic in sight that you should line up up behind (e.g. "Speedbird 123, report Lufthansa A320 on short final in sight") . Only after replying (e.g. "Lufthansa A320 on short final in sight, Speedbird 123") will ATC give you a conditional clearance. In this example it would sound like "Speedbird 123, behind landing A320, lineup runway 25 and wait behind". A full readback is required. In some places will NOT ask you to report the traffic in sight, it all depends on local ATC rules (lawyer stuff...). Important is the fact the word "behind" is mentioned twice: as part of the description what to do and then again at the end of the instruction. You must read back "behind" two times as well.

Note: conditional clearances can happen with traffic on the runway in front of you and with traffic still in the air, coming in to land on the runway that you are going to depart from.

PS: Skybrary has a nice article about it, highlighting the risks and urging pilots to make accurate readbacks and identifying the plane in question without doubt. If in doubt, don't accept the clearance, ask ATC:https://skybrary.aero/articles/conditional-clearance

Edited July 29, 2022 at 04:05 PM by Andreas Fuchs

[Richard Lee]

1 hour ago, Alex Ying said:

You will never get a LUAW instruction while an aircraft has been cleared to land on the same runway, but you may get a LUAW instruction with an aircraft on approach but not yet cleared to land. That would sound like this:

• "JBU123, runway 15, line up and wait, traffic on a 3 mile final." You should immediately start moving across the hold bars and line up on the runway since the controller is trying to get you out before the next plane lands. You should expect a takeoff clearance pretty soon since the traffic is only about 1-1.5 minutes out from the runway. You would probably also hear the controller issue a landing clearance to the traffic behind you, but only after you've been cleared for takeoff

Wow, the timing for this sounds tight. If I am given an instruction like this in real life, and I don't immediately move onto the runway and take off,  and somehow the approaching aircraft misunderstood ATC and think they were given clearance to land (which I would guess has happened in real life before), this sounds like a disaster waiting to happen.

[Richard Lee]

1 hour ago, Don Desfosse said:

2b. Yes, you would make sure you didn't hit or get blown over by the departing aircraft, and then line up and wait as discussed above.

 

Hope this helps!

 

Ahh, thanks.  So a conditional "line up" means you have to wait for the condition to occur, and then you can execute the instruction. Also good to know conditional clearance with LUAW cannot happen in the US.  I think I got it.  Thanks!

Edited July 29, 2022 at 05:03 PM by Richard Lee

[Richard Lee]

1 hour ago, Andreas Fuchs said:

Outside the US, you will come across conditional clearances every now and then. In some places ATC will ask you first whether you got the traffic in sight that you should line up up behind (e.g. "Speedbird 123, report Lufthansa A320 on short final in sight") . Only after replying (e.g. "Lufthansa A320 on short final in sight, Speedbird 123") will ATC give you a conditional clearance. In this example it would sound like "Speedbird 123, behind landing A320, lineup runway 25 and wait behind". A full readback is required. In some places will NOT ask you to report the traffic in sight, it all depends on local ATC rules (lawyer stuff...). Important is the fact the word "behind" is mentioned twice: as part of the description what to do and then again at the end of the instruction. You must read back "behind" two times as well.

Note: conditional clearances can happen with traffic on the runway in front of you and with traffic still in the air, coming in to land on the runway that you are going to depart from.

PS: Skybrary has a nice article about it, highlighting the risks and urging pilots to make accurate readbacks and identifying the plane in question without doubt. If in doubt, don't accept the clearance, ask ATC:https://skybrary.aero/articles/conditional-clearance

So  "Speedbird 123, behind landing A320, lineup runway 25 and wait behind" means:

1. I have to wait until the Lufthansa A320 has landed first
2. And the Lufthansa A320 is in front of me after it has landed
3. If conditions 1. and 2. above are satisfied, then I can enter the runway 25 to line up.  However, I am still not given clearance for take off. I am just lining up on runway 25, waiting for clearance for takeoff.

Ok, I think I got it! The link was very helpful in understanding what a conditional clearance is. Also good to know that conditional line ups don't happen in the US, but can happen outside the US.

I also assume that if the Lufthansa A320 never lands (ie. it goes around), conditions 1. and 2. are not satisfied, so I cannot enter runway 25 and I have to wait for further instructions from ATC.

Edited July 29, 2022 at 05:08 PM by Richard Lee

[Andreas Fuchs]

3 hours ago, Richard Lee said:

So  "Speedbird 123, behind landing A320, lineup runway 25 and wait behind" means:

1. I have to wait until the Lufthansa A320 has landed first
2. And the Lufthansa A320 is in front of me after it has landed
3. If conditions 1. and 2. above are satisfied, then I can enter the runway.

Ok, I think I got it!  Also good to know that conditional line ups don't happen in the US, but can happen outside the US.

Yes. You can already perform your lineup do-list and checklist (landing lights ON, strobe lights ON, transponder/TCAS to TA/RA, inform cabin crew etc.) while you are waiting for the plane in question having moved past your position and the runway is clear for your to line up. This way you will be ready to line up without delay and be ready for departure.

Edited July 29, 2022 at 08:09 PM by Andreas Fuchs
Nicer formatting

[Robert Shearman Jr]

Great questions, Richard.  Awesome to see new VATSIM pilots this concerned about making sure they understand what they're instructed to do -- and why.

[Liesel Downes]

I was the controller for that stream you're referencing and I love to see threads like this asking for clarification on things you've seen out on the network. Great learning experience for everyone 🙂

[Michael Flemming Hansen]

When you are asking to line up (and wait) on a runway, you are given permission to enter the runway. So yes, you may enter the runway. Whether you are holding at the line (and thus just given the instruction "line up and wait") or you are taxiing towards the holding point and given the instruction you mentioned "via A12, line up and wait".  So:

N978CP  = You.

via (holding point) = Using holding point mentioned

line up runway 15 = Enter runway 15 and remain stationary after positioning yourself for takeoff

 

I can see where you are getting at with the conditional instruction, but again, it is it implied in the instruction that you don't roll into the other plane. So, to break it up.

Behind the departing Southwest 737 = When the SW 737 has begun its takeoff roll and is safely at a distance from your plane

via A15 = Using the holding point A15

line up runway 15 behind  = Enter the runway and remain stationary when positioned for takeoff. 

When the times come, you may even get a takeoff clearance like this:

N978CP, winds are 179 degree at 2 kts, runway 15, cleared for takeoff, mind the turbulence from departing jet. 

It is important to remember, essentially, that you as PIC are the boss. You have the final say regarding the safety of yourself, your crew and your passengers (This is of course a bit more relaxed in a simming environment).