Wake Turbulence calculations different in UK and Europe?

[RAPA Pilot]

I've just read SI to MATS Pt1 (CAP493) on the CAA web site. Do these figures apply to European airfields?

Yesterday at an airfield in Germany we (light, MTOW 9tons(according to CAP493)) were departing behind a B738(Medium). I started my stopwatch as the nose wheel of the B738 rotated. We were given line up and take-off clearance after 40 seconds. I complained but was told the 738 was now 4 miles ahead. huh?????? Never heard that before.

So by what do European ATCOs work to when calculating Wake turbulence seperation minima for departing aircraft?

[Data Dad]

Wake Turbulence calculations different in UK and Europe?
Yes, because UK is different to ICAO when categorising for Wake Turbulence. Under ICAO categories your MTOW of 9T is classed as a Medium for Wake Turbulence.

ICAO - Light <7000Kg, Medium 7000-136000Kg, Heavy >136,000Kg

UK - Light < 17000Kg, Small 17000 - 40000Kg, Lower Medium 40000 - 104000Kg, Upper Medium 104000 - 162000Kg, Heavy > 162000Kg

Under ICAO guidance, individual States may elect to use variations.

HTH

DD

[Nightrider]

Is it official now that the UK is not Europe????

Well, here what the web offers:

Eurocontrol (http://www.eurocontrol.int/eec/public/standard_page/EEC_News_2008_3_RECAT.html), watch the weight mentioned, you are also medium.

UK CAA (http://www.caa.co.uk/application.aspx?catid=33&pagetype=65&appid=11&mode=detail&id=3461)
it says: 9.6.1 Wake turbulence separation minima on departure shall be applied by measuring airborne times between successive aircraft. Take-off clearance may be issued with
an allowance for the anticipated take-off run on the runway; however, the airborne time interval shall reflect a difference of at least the required time separation.

Means that the allowance part was used; 40 seconds + 5 seconds for you to react and grabbing the microphone + 10 seconds for radio call and lights + 25 seconds for your own line-up + 40 seconds for your own take-off run that equals 2 minutes, the bare minimum. If you move slowly into position and delay by 10 seconds or 15, you will get even more separation...

Wikipedia (http://en.wikipedia.org/wiki/Wake_turbulence)

Take-off separation is purely based on timings. Separation based on distance is used for approach and landing...

[ron83]

However haven't seen in ICAO doc's about distance wake turbulence separation for departure,have seen it in Local procedures of different airports...;)

[RAPA Pilot]

As I understood it the eurocontrol classification is for enroute planning purposes and would then use distance. How would that be relevent to a tower contoller in Germany and a departing aircraft which should use time?

Means that the allowance part was used; 40 seconds + 5 seconds for you to react and grabbing the microphone + 10 seconds for radio call and lights + 25 seconds for your own line-up + 40 seconds for your own take-off run that equals 2 minutes, the bare minimum. If you move slowly into position and delay by 10 seconds or 15, you will get even more separation...

Nightrider, it doesn't take 40 seconds for a 9T jet to rotate and no allowences were applied. We were lined up fully ready when the TO clearence was given. 40 seconds had elapsed since the 738 had rotated.

OK
4 seconds to reply, "Cleared take off xxxxxxx'
2 seconds to say 'checks complete'
15-25 seconds to rotation.

Yes, because UK is different to ICAO when categorising for Wake Turbulence. Under ICAO categories your MTOW of 9T is classed as a Medium for Wake Turbulence. In what phase of flight?

Is it 2 minutes in Germany as it would be in the UK or not? Is it wise for a 9T aircraft to be taking off to close to a 79T aircraft? I don't think so.....

[ADIS5000]

RAPA,

The point that the previous posters were making is that in Germany you and the 737 are in the same Wake Turbulence category. ie You are a Medium under ICAO rules (>7tonnes). In Germany therefore, there is no requirement to give you the 2 minutes you were expecting. The CAP 493 is for UK use only. When the Tower controller replied that you had 4 miles they were probably trying to re-assure you that the preceding aircraft was clear ahead, they would not be thinking that there was a Wake Turbulence issue. Under ICAO rules you are a Medium category aircraft and that is what will appear on your flight plan info. This info will be used on both departure and final approach phases of flight. Do I think (as a UK ATCO) that it's a good idea to launch you up the chuff of a 737? Not really, but ICAO says its okay. Next time, whilst you are at the holding point, advise the controller that you are requesting a 2 minute gap before you are airborne.

Regards, ADIS

[radarman]

Although RAPA Pilot was flying a 'Light' (UK definition) aircraft, presumably he would have had to file 'M' on his FPL as the form only accepts ICAO categories. Hence no wake turbulence separation from the German controller.

How does ATC at UK airfields re-categorise the ICAO turbulence category on the FPL into the differing UK categories?

[Nightrider]

RAPA,

you said:
We were given line up and take-off clearance after 40 seconds.
this gave me the assumption you were not on the runway yet.

Be aware that even a 2 min separation between a "light" 738 at about 64 to behind a "heavy" 321 has to deal with some interesting aileron inputs and my coffee does not stay in the cup....

You mention 15 - 25 seconds to rotation....never achieved this in any turboprop I flew, and that was the Cheyenne, Metro, Saab340, F27.

In a situation like your one behind a jet, why not slow down a bit and make life easier for you and others. Smooth line-up, smooth adjusting of thrust, and your 2 minutes are available.

Fly to Paris, any airport....
Fly to Stansted in CATIII....

Separation is today at the limit during certain times of the day.

Get me right, I do not think that the separation you were provided with complies with any safety aspect, but bean-counters find it safe. And they make the laws.

Sentences like: Limits are there to be reached, not to be observed.

[RAPA Pilot]

When the Tower controller replied that you had 4 miles they were probably trying to re-assure you that the preceding aircraft was clear ahead, they would not be thinking that there was a Wake Turbulence issue.

The controller SHOULD be thinking 'wake turbulance' all the time!!!!!

advise the controller that you are requesting a 2 minute gap before you are airborne.
The last time I told tower I wasn't ready I was shoved off the runway and had to queue up again. Grrrrrr!!!

You mention 15 - 25 seconds to rotation....never achieved this in any turboprop I flew, and that was the Cheyenne, Metro, Saab340, F27. Nop...never achieved this in any Turboprop I ever flew either.

...but bean-counters find it safe. And they make the laws.
Sentences like: Limits are there to be reached, not to be observed.
Yer I understand that and agree but the bean-counter is not stood next to the guy in the tower and I'm sure he doesn't want a fatal on his watch.

Seperation, either in distance or time, is a minimum not a limit.

My question still stands. Perhaps a German ATCO can tell me by what standard do they calculate take off seperation minima???? And is there any ATCO discression?

[Geffen]

Always tell the tower BEFORE you line up if you require more than the standard. This way it solves any problems. The tower should have no problem accommodating the request.

[RAPA Pilot]

Absolutely Geffen, but tell me, what is 'the standard' ?

[Geffen]

Good point, unfortunately I guess you pilots will have to brief on the expected standard applied in each country you fly to. Deviations from ICAO standards are the cause and until they are universally applied, well you get the picture.

[Fesch]

AFAIK german tower controllers have a radar licence, and they are allowed to apply radar separation. But I will check this with a german friend and come back to you.

[criss]

If you're in a 9T jet that rotates in 15-25s (I see this happen quite a lot), then most probably you'll never enter the path of 738's vortex - you simply outperform him.

[Dan Dare]

RAPA Pilot Absolutely Geffen, but tell me, what is 'the standard' ?

The standard is that if no Vortex separation is required then no vortex separation will be provided (unless considered necessary by the pilot or controller). As a Medium you are the same category as the Medium that rotated ahead of you and the controller can legitimately give you take-off as soon as there is daylight under the wheels of the leading aircraft if there are no IFR separation criteria to comply with. In the UK you magically become a Light vortex wake category and the ATR that could depart immediately behind you in Germany must now wait 2 minutes.

Please always tell the tower if you believe that you will require more Vortex spacing than they need to give you (presumably when you are flying outside UK) before you enter the runway. With experience you will get to know when to do this. Tower should also know that the request could be forthcoming because you are another one of those Englisch.

Interestingly, there is no longer any Wake Vortex. They think it simplifies everything if they call it Wake turbulence now.:rolleyes:

[RAPA Pilot]

If you're in a 9T jet that rotates in 15-25s (I see this happen quite a lot), then most probably you'll never enter the path of 738's vortex - you simply outperform him.
Yesterday 22:49
Having given this some thought over the last few days and spoke to a pal of mine who is a Captain on the 738 and with several others more experienced then myself I have had confirmed what I had suspected. I will almost always out perform the 738.
Having had a terrifing wake turbulance experience some years ago which nearly cost me and 11 pax their lives I am, as I am sure you will understand, a little more aware of the consiquences of such an encounter.

Please always tell the tower if you believe that you will require more Vortex spacing than they need to give you (presumably when you are flying outside UK) before you enter the runway.
And that is really my point. If I don't know he is not going to give it to me then I dont know I need to ask. But lesson learned, I will be more aware next time.

[ILS 119.5]

Hey Guys/Gals,
Look at your company rules. Forget what the ATC people tell you, if they clear you for take off and you do not think you have the required time because of vortex problems then don't go. Similarly, if you are behind a larger aircraft and you know what distance you require then ask the question to the controller. Do not put yourself or your passengers in danger by being under pressure to do your job.
Take out there.

[TWR]

Yes but consider your options BEFORE you enter the runway. "Ready for departure" really is what it means. 2 minutes WT separation is measured from airborne-time to airborne-time, not from airborne-time to clearance received/start-rolling-time. I never refused additional separation when requested by the pilot. But if you ask for it when already lined-up on the RWY and there is landing TFC 6 miles out you'll have to vacate the RWY and join the queue at the end.