Aerodrome Light Signals. HELP?

[MXB300]

Hello Forum,
Firstly apologies If I am posting this in the wrong section.
I'm currently working my way through my PPL exams - I'm slightly confused by the section of Aerodrome lights signals given to aeroplanes in the air and on the ground.

First Question:

Flashing green light to a plane in the air means "Return for Landing"
&
Steady Red light to a plane in the air means "Give way continuing circling"

How are these two light signals different?

Second Question:
What produced more severe wake turbulence? Heavy aircraft in the clean configuration or heavy aircraft in the dirty configuration?

Many Thanks,
Matthew.

[150 Driver]

Welcome Matthew.

The light signals.... The difference between them is that one is green and flashes the other is red and doesn't:ugh:

Seriously the difference is flashing green to an airborne aircraft is that they want you back on the ground, having (presumably) just departed. I can't think of why, my Instructor used to say it was that you've departed without paying the landing fee.

Whereas the red to airborne aircraft is intended to say that you will probably be given a (solid) green to land at some point but not yet, so stick around and you'll get down. This contrasts with flashing red which is basically you being told to :mad: off somewhere else.:=

I couldn't see the point of knowing any of this until my first flight post PPL saw me lose my radio...

As for wake turbulence I would have thought dirty configuration but am guessing

Good luck

[skyhighfallguy]

first...heavy clean


flashing green return for landing TO BE FOLLOWED BY STEADY GREEN FOR LANDING CLEARANCE

Steady RED while in the air means continue circling and give way to everyone else.

it is likely that if you get flashing green it will VERYsoon be followed by landing clearance

if you get steady red you could be there all day as in maybe the runway is damaged.

for NOW ,just memorize it by rote. NOTHING is wrong with ROTE memorization, full understanding will come with experience.


someday you might even learn about RED RIGHT RETURNING and you can ask about that. but just learn the stuff, and understanding will come.

[Tarq57]

These things are archaic. I believe the signal meanings have not been updated (translated to modern terms) since WW2.

Effectively a flashing green means "continue approach." (It says "return for landing" A flashing white given to an aircraft in the air is less equivocal; "return to land at this aerodrome").

A steady red means, depending on your best guess if it happens, "orbit", or "circle the aerodrome".

Doesn't everyone carry cellphones these days? Last genuine radio failure I experienced as a controller we simply rang the aero club, asked for the students mobile number, gave her a call, and subsequently an approach/landing clearance.

I'd learn the meanings verbatim for the theory test, but in the real world, rely on something else, frankly.

[daveborg]

Not to confuse a student, but I'd have thought a heavy/dirty configuration would produce more wake turbulence. Wake turbulence is caused by the differential in the air pressure between the top and bottom of the wings. As these meet -at the wing tips, and the edges of the flaps- they cause vertices or violently spinning air. Think a mini horizontal tornado.

A heavy aircraft with flaps and gear out is flying at a higher AOA, therefore higher pressure difference.

[fujii]

www.airservicesaustralia.com/wp-content/uploads/wake.pdf

[skyhighfallguy]

Checkride Heavy, Clean, And Slow - Flight Training (http://flighttraining.aopa.org/magazine/2001/January/200101_Training_Topics_Checkride.html)


here it says that Heavy Clean and SLOW is the worst

[Fishtailed]

Doesn't everyone carry cellphones these days?

Er, no, I would say:rolleyes:

[AV83R]

Heavy, clean, slow. 100% the right answer

[skyhighfallguy]

AV83R

thanks for verifying. might be counterintuitive to some, but hey, that's why there are CFIs, right?

[MarkerInbound]

So you're out flying and your radio quits. Some how the tower notices this and shines a steady red light at you. So you circle. Do you fly a holding pattern, fly 360s, fly the traffic pattern but do not descend, obit the field three miles out? Circling is a very broad term. At some point the tower gets tired of you and realizes you're not going to depart the area for the uncontrolled field 10 miles away so they flash the green light at you. So now you set up for landing and you hope to see a steady green light on final.

[ShyTorque]

At some point the tower gets tired of you and realizes you're not going to depart the area for the uncontrolled field 10 miles away

If they wanted you to go elsewhere, they would show a flashing red light.

[fujii]

If they wanted you to go elsewhere, they would show a flashing red light.

No, the tower wouldn't. Flashing red, aerodrome unsafe, do not land. No requirement to go away.

[AV83R]

Skyhighfallguy,

The best way to explain it is to use the lift equation, L=Cl1/2PV^2S (sorry I can't use the actual mathmatical symbols). We say that heavy, clean and slow produce the greatest vortices.

To counteract weight, there needs to be lift, the heavier the aircraft the more lift required. So using the formula:

Assume an aircraft has full flaps, but reduces its airspeed from a nominal value of say 100KTs to 80KTs, to maintain the same amount of lift he needs to increase the Cl

Assume no flaps, so a reduced surface area to the first scenario, but he flies at 100KTs, he still needs to increase the Cl to maintain the same amount of lift

So adding these all in, if an aircraft has no flaps, and a low speed he needs an even further increased Cl to balance the equation. With that, we can then deduce why heavy, slow and clean is the worst configuration. Wing vortices increase in strength as the "deflection angle" increases ie. the angle of attack (which is the thing that changes the Cl of an aerofoil).

I hope this helps, but I'm sure there is someone here that can explain better

[skyhighfallguy]

AV83R

no, I understand it. I was making the counterintuitive comment for the other poster who got it wrong.

he is in need of the cfi (of which I am one)

all the best

[AV83R]

Haha sorry mate, I thought you were the OP. I'll shut up now :ugh:

[xrayalpha]

Hi MXB300,

Welcome to pprune.

Your two questions are typical of "exams" and "studying": ie not really relevant, at least in the way they are typically asked.

To treat the "heavy" one first: what people want you to know is that:

1. Induced drag (sometimes known as lift-induced drag) is directly proportional to lift. So, increase lift, increase induced drag.

2. To get more lift on a wing, you either have to fly faster (and get more air over it) or if you fly slower, then you get less air over it, so that air has to be used more efficiently. To do this, you increase the angle of attack of the wing.

3. As you increase the angle of attack, the lift-induced drag - ie wing vortices - increases.

4. Those vortices are the main contributor to wake turbulence.

So, a heavy aircraft "clean" will actually have to have a higher angle of attack to generate lift. So create more turbulence.

Now, you may ask, when might you get in a situation at your local airfield where a heavy is going to fly by "clean". And if you do, you are probably at an airfield where there is a tower with full ATC. And if there is, they will have separation minima which they will make you hold for.

So to me, the point of the question is to explore lift/drag etc, and not a "real world" this is what to do answer.

As for lights.

The Air Pilot does say you can fly into Glasgow International without a radio! No-one has done that for decades! I doubt Glasgow even has light signals, but could be wrong.

I know at another, smaller, licensed Scottish airfield, the Health and Safety said it was too dangerous to have batteries in the control tower. So they would have to be stored downstairs in a vented cupboard. Or why couldn't the light just be plugged in? Of course, the point for the airfield having batteries was if the power went off!

The answer there was that they have hand-helds, the fire truck has a radio and they allow non-radio traffic anyway. So if the aircraft radio fails, not an issue either.

As to light signals working, read the Flight of the Gin Fizz - a deaf US pilot following in Calbraith Rodgers first trans-continental flight route. Basically, being deaf he couldn't hear the radio. Even after contracting many airfields and being told they would use lights, he never saw the lights most times. Sometimes, airfields that said they had lights, didn't!

Me, if non-radio I would rather look out for other traffic than for non-existent lights!

[BackPacker]

I'd learn the meanings verbatim for the theory test, but in the real world, rely on something else, frankly.

Just last week a mate of mine was returning to a controlled field when his battery died. Apparently his alternator had given up earlier but he had never seen the warning for that. By the time his electrics failed he was well into the CTR, about to get his joining instructions.

His cellphone was in a bag in the back. Theoretically his passenger could have gotten it out and he could use that to call someone. That would have taken him, perhaps, five minutes. While holding in a CTR with several aircraft following him on the same arrival route. Not a good idea.

Fortunately the tower was on the ball (the lack of not just radio, but transponder as well must've given them a clue) and gave him light signals. He was safely on the ground a minute later. No drama whatsoever.

In addition to that - have you ever tried making a phonecall from inside the noisy cabin of a GA aircraft?

Personally, I think light signals are still a very good idea, even in 2015. If you remember red = bad, green = good, then you're halfway there.

[Gertrude the Wombat]

Sometimes, airfields that said they had lights, didn't!
I once asked the controllers at Cambrige. The guy said he thought he knew where to find them.

This query prompted me to look in Pooley's, which is the only book I carrywith me in the aircraft, to check whether it did actually have crib sheets for

- light signals
- marshalling signals
- interception procedures

these all being things that you never use but might, just, be useful once in a lifetime, and was somewhat disappointed to find that it didn't. One for the next edition chaps?

(I did have to follow a marshaller once, on a weather diversion to somewhere I hadn't planned to land. He waved his arms around, I went in the direction he was pointing. Seemed to work.)

[ShyTorque]

No, the tower wouldn't. Flashing red, aerodrome unsafe, do not land yet. No requirement to go away. If you're going to be pedantic, rather than practical, that's not the meaning of a flashing red as defined in CAP637.

The advice given therein: (Flashing red light to aircraft in flight)

"Do not land, airfield closed".

There is no inclusion of the terms "unsafe" or "yet".

If you have plenty of fuel, I supose you could continue holding off, in anticipation of the re-opening. But it might not be today, of course. If you did so, you wouldn't endear yourself to the ATC'er who has to continue pointing the flashing the red light at you, until either the airfield re-opened, or you ran out of fuel and took the advice as intended.

[fujii]

Thanks for that Shy Torque, I'll try and remember that if I ever fly in your country.

[londonblue]

In addition to that - have you ever tried making a phonecall from inside the noisy cabin of a GA aircraft?

Yes, and it was extremely easy. I couldn't hear a bloody thing, but making the call was simple! Joking aside, though, isn't that becoming easier with new headsets that allow you to plug in, or bluetooth your phone?

This query prompted me to look in Pooley's, which is the only book I carrywith me in the aircraft, to check whether it did actually have crib sheets for

- light signals
- marshalling signals
- interception procedures

Good idea. I got marshalled at Le Touquet once, but had completely forgotten the signals. I did go home and relearn them, but must confess I've probably forgotten them again.

[Jim59]

The only time I have ever been given light signals was many years ago when on short final to land at a grass RAF airfield in a glider - they had obviously just noticed me - and gave me a green.

What should I have done if they had given me a red? I know what I would have done.

[150 Driver]

The only time I have ever been given light signals was many years ago when on short final to land at a grass RAF airfield in a glider - they had obviously just noticed me - and gave me a green.

What should I have done if they had given me a red? I know what I would have done.

I guess if you're on a short final in a glider you continue to land and deal with the paperwork afterwards...

[Big Pistons Forever]

Green = Go

Red = Whoa

Simples..

[Sir George Cayley]

Can I recommend CAP637 The Visual Aids Handbook?

CAP 637: Visual Aids Handbook | Publications | About the CAA (http://www.caa.co.uk/CAP637)

A right riveting read!

SGC

[ShyTorque]

Can I recommend CAP637 The Visual Aids Handbook?

As per post #20. ;)

[no slots]

A steady red would normally be shown to an aircraft on final when it is unsafe to land from that approach. The action would be to go around and reposition in the traffic circuit for another approach giving way to other aircraft as necessary. ie; don't turn early to reposition onto final and cut up the pattern already being flown.
Hope that helps:)

[Sir George Cayley]

Was it James Hunt who said "what marshals?" :ok:

I've shone all matter of light signals at a/c and been generally ignored. Most pilots said they never saw anything.

SGC

[FantomZorbin]

A red Verey flare just in front of the aircraft tends to attract attention!!! :E

[riverrock83]

Glasgow do have light signals - saw them on a tower visit. I suspect there is a requirement for all towered fields to have a set.
I do think they have their place although they can be pretty hard to see during the day. Worth asking your instructor to arrange with the tower if you can do some non-radio practice with them. Controllers are often happy to have an excuse to do something a bit different!

[mikehallam]

Got a Green from the Tower at RAF Colerne many years ago arriving non radio, a short while before their official opening time, in my 65h.p. Nord NC854S.

So happily landed forthwith. To get a b**llocking as they'd not shone me a Green

It turned out it was the Sun shining off glass top tables through their green tinted Tower glazing. So I was half forgiven.

mike hallam

[Pull what]

First Question:

Flashing green light to a plane in the air means "Return for Landing"
&
Steady Red light to a plane in the air means "Give way continuing circling"

How are these two light signals different?

The flashing green is a local recall signal for aircraft outside of the circuit:

The steady red means, 'go around'.

Steady signals are the important ones and can all be sent by flare.

Light signals are still occasionally used at some airfields for normal movements, Old Warden for instance and some airfields where gliding is taking place.

Second Question:
What produced more severe wake turbulence? Heavy aircraft in the clean configuration or heavy aircraft in the dirty configuration?

These two type of questions(lights and wake turbulence) are found in the Operational Procedures examination and for the wake turbulence question you need to know the contents of the AIC, rather than the aerodynamic theory

The correct examination reference document for Wake Turbulence questions in the Operational Procedures examination is

http://www.ead.eurocontrol.int/eadbasic/pamslight-75EB2729C495BD530B65F06300E0ABD6/7FE5QZZF3FXUS/EN/AIC/P/001-2015/EG_Circ_2015_P_001_en_2015-01-22.pdf

The above AIC was only updated a few months ago so it’s something every UK pilot & flying instructor should know about and interestingly no one quoted!.

and of course

http://www.caa.co.uk/docs/33/20130121SSL15.pdf

There is no need to go into complicated aerodynamic theory as Xrayapha has done and dug himself a hole and got some of it it wrong!

Wake turbulence is produced by the pressure differential between the lower and upper wing surfaces (induced drag) which is considered to be at its greatest at the highest angle of attack before the critical angle with flaps zeros (This is the answer the CAA want but some aerodynamicists far more knowledgable than me disagree with this)

Your two questions are typical of "exams" and "studying": ie not really relevant, at least in the way they are typically asked

These questions are completely relevant to the syllabus you are studying, making a statement like that, which may be representative of your attitude and knowledge(or lack of it in this case) encourages people to skim through text rather than try and learn and understand it.

The examination is an academic exercise designed to test your knowledge and understanding of published operational procedures which may or may not be relevant to the type of flying you are engaged in at the moment or in the part of the UK that you fly in at the moment. The misunderstanding of that relevance doesn't help with examination preparation. Treating the exams and the associated preparation as an academic exercise not only helps with the final result, it also creates a better attitude to flying in general and its the attitude you take to the aircraft that will eventually decide your destiny in it!

To treat the "heavy" one first: what people want you to know is that:

In fact what 'people' (the examiner) wants you know is that there is an AIC that deals with Wake Turbulence and that you have read it.

Now, you may ask, when might you get in a situation at your local airfield where a heavy is going to fly by "clean". And if you do, you are probably at an airfield where there is a tower with full ATC. And if there is, they will have separation minima which they will make you hold for.

A 747 recently flew into Kemble and they do not have ATC. Controllers are also just as capable of making mistakes as pilots and just relying on ATC to provide separation is hardly a thinking pilots best situation awareness plan is it?

I use this sad fatal accident on our briefings. This pilot was a panel examiner and CFI at CSE Carlisle and probably one of the UKs most experienced and qualified instructors at the time

https://assets.digital.cabinet-office.gov.uk/media/5423046a40f0b61342000b75/2-1980_G-AYMJ.pdf

As for lights.

The Air Pilot does say you can fly into Glasgow International without a radio! No-one has done that for decades! I doubt Glasgow even has light signals, but could be wrong.

Really? I would love to know where in the The UK Integrated Aeronautical Information Package (IAIP) it says that you can fly into Glasgow without a radio, perhaps it did when that document was called the Air Pilot.

What is does say is:

EGPF AD 2.20 LOCAL TRAFFIC REGULATIONS

1 Airport Regulations
(a) Use governed by regulations applicable to Glasgow CTR

and as Glasgow CTR is class D airspace you must be in radio contact with ATC ( ENR 1.4 2.4)

AD 2.20 will also tell you that there are no ground signals but there may be light signals! You would do well to actually read what you are trying to quote from!