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Topic: I Experienced A Near Miss With Snba To LHR
Username: Dragonrapide
Posted 2002-08-20 13:26:58 and read 3282 times.

Last Friday, I was on flight SN3815 from BRU to LHR. The pilot had informed us that we would be landing on runway 9L instead of 27R because of the wind direction. It was my 23rd time to fly to LHR and only the second time the landing would be from that direction.
Everything was normal. Weather was perfect: good visibility and no clouds. Flaps and slats went out, gear went out. And then suddenly we were shaken very very hard by turbulence. Immediately the pilot initiated a turn simulatneously resetting the flaps and retracting the gear. He climbed to a flight level similar to that of a holding pattern and leveled of.
Then, the pilot made following announcement: "Dear passengers, on finals we came rather close to a 767 and flew through his wake turbulence."
I had figured that much out myself. We were shaken very hard in the turbulence. The 767 couldn't have been too far away although I guess its wake turbulence has a rather big effect an a relatively small aircraft like a Avro RJ100.
Anyway, the second attempt was without any hick-ups.
For me, it was the second time that an approach had to be broken off on a total of 162 flights. The first time was due to a malfunctioning ILS when we were trying to land in a very foggy Geneva. That wasn't too bad because the landing was aborted when we had still some height. Now we were relativley close to the ground when we were hit by the turbulence.
I guess when an airplane hits the turbulence of another airplane that hard, we were too close and that it was a near miss. Especially since the pilot reacted in taking such immediate action. If it had been turbulence without any aircraft close by we could have easily continued our landing.
Has anyone else experienced anything similar?

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: J-bird
Posted 2002-08-20 14:04:10 and read 3209 times.

Your post highlights an interesting problem, and one that appears to be increasing in the crowded European airspace - wake turbulence encounters. About 2 years ago, I was on a BA flight from Budapest to LHR and while still over the English Channel, but descending into the pattern, the aircraft jolted violently to the left twice in rapid succession. This was severe enough that people were screaming and a couple of passengers were injured.

The pilot reported that ATC had put us too close to the aircraft in front, with the resulting wake turbulence causing the two dives.

It highlights the need for more slots around London and makes a potential argument against the practice of more flights, in smaller aircraft (as opposed to fewer flights, but in larger planes).

Interesting experience, but one I am not keen to repeat.

Cheers.

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: Erasmus
Posted 2002-08-20 14:26:04 and read 3177 times.

The word "Near miss" should not have been used here. A near miss happens when 2 A/C inadvertently come too close and there is a risk of collision.

On final, very often, jet aircraft come as close as 3 NM from each other, without any risk of collision.
In calm weather conditions (no wind or thermal activity) wake turbulence can affect aircraft even if they are 6 or more miles apart. The lighter the aircraft, the more "sensible" it is to wake turbulence from a preceding heavy a/c.

The pilot made the right decision by executing a go-around.
Situations like these occur dozens of times every day at many airports.

Not really a big deal!

Regards,
Erasmus.

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: Apuneger
Posted 2002-08-20 14:35:53 and read 3146 times.

Although I find your story rather interesting (I've never experienced something like that, but it must be scary, I admit that), I think your topic title is a bit over the edge, don't you think? I'm sure it wasn't a near miss, your aircraft just got caught by the wake turbulence of a 767. And this sort of turbulence can last for a couple of miles, I'm sure of this. You guys were even flying in the same direction.

So, interesting story indeed, just overreacted a bit with your title. Forum users that don't read the whole story but only get to see the title now will probably start thinking 'oh no, SN BA is really bad for safety' or something like that, don't you think?

Ivan

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: Broke
Posted 2002-08-20 14:46:17 and read 3121 times.

You don't have to be very close in an AVRO RJ100 to a 767 to be pretty badly shaken by its wake turbulence. The worse possible state would be one in which there is little or no wind to either dissipate or move the turbulence off the flight path. Then fly in trail of a heavy but below its flight path. The wake vortices will stay in line and descend behind the airplane generating them. Wake turbulence seems to be greater behind a slow moving heavy, so it is more likely to be encountered during the approach phase when the airplanes are in trail and following the same descent profile.

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: Airbus_A340
Posted 2002-08-20 14:49:17 and read 3113 times.

Erasmus, shouldn't that be a 'near hit'?
Because it more sounds like they nearly hit it rather than nearly missing it, which to me, doesn't make much sense!

Trevor

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: Sab12
Posted 2002-08-20 15:12:20 and read 3094 times.

This often happens at Heathrow, if the aircraft comes to close they will pick one out in the line, remember Heathrow is one of the busiest airports in the world, this is usual there

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: Redngold
Posted 2002-08-20 15:19:53 and read 3074 times.

I was involved in a true "near miss" at PHL in 1998. I was on an Allegheny DH-8-100 (USAirways Express) landing on Runway 9R and we initiated TOGA just over the threshold. Good thing, because I looked out the starboard window and saw a white-topped (Continental?) MD-80 flash by on Runway 18, directly underneath us!

redngold

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: Dragonrapide
Posted 2002-08-20 15:23:31 and read 3071 times.

I sure hope both aircraft were flying in the same direction!
So, I take your point about near miss maybe not being the appropriate name for this incident.

Although as I said I didn't see the 767 (probably only the pilots had it insight since it was landing before us), we were shaken VERY VERY heavily. With 162 flights behind the belt, believe me, it wasn't the first time I encountered turbulence. I once was in a ERJ-145 on approach to Bilbao when we flew thorugh a heavy thunderstone on approach. That turbulence lasted much longer but wasn't as heavy as the one on approach to LHR believe me. Even the stewardesses looked a bit pale.

@ Apuneger: "Forum users that don't read the whole story but only get to see the title now will probably start thinking 'oh no, SN BA is really bad for safety' or something like that, don't you think?"
That would be the wrong conclusion and is certainly not what I wanted to say. Afterall it is the ATC that directs the planes so if someone screwed up it's them.

@ Erasmus: I saw in your profile that you are a pilot. Now for academic reasons, what is the definition of a near miss?Near miss = when two planes come into each others airspace without reference to their direction? I understand that each airplane flies in a 'box' of x y z dimension. If the 'box' of another airplane enters the 'box' of the first one, would this be a near miss?
Example: a slow flying airplane is being overtaken by a fast flying airplane on a parallel course but a different height. No risk of collission but both had not enough vertical separation. Is this a near miss?

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: VirginFlyer
Posted 2002-08-20 16:14:50 and read 3028 times.

Airbus_A340 - Near miss is the correct terminology - it means a miss that was near, not nearly a miss.

V/F

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: Turbulence
Posted 2002-08-20 16:15:51 and read 3025 times.

In this case I'd like to pose a question.

For sure a 767 and an RJ100 do not need the same rwy length for landing. Can't say if tha stall speed is the same or similar for both, but I suspect that it can be quite lower ofr the Avro.

We all know how busy big airports are, and that it is perfectly possible for the landing queue have different combinations of heavies and light airplanes. I assume that minimum separation must be kept between consecutive landers (imagine how far back a Concorde should hold behind an ATR...), and that it happens very often that an RJ or an ATR is landing behind a 767 or 747, etc., etc. I know also that ILS guides all pilots to follow the same pattern/gliding path, meaning that the wake turbulence of a heavy should not affect a small aircraft. But it happens. The other thursday at BCN a BAe146 was cleared to align rwy 20 for T/O right behind the QF744, and asked how long wanted to hold behind. The answer was 30 secs. I mean, every small aircraft is warned of a heavy in front. When Dragonrapide's captain was informed that was landing behind a 767, could he/she have approached slower and slightly higher in order to avoid the 767's wake? This would have made the tiny RJ touch down 400 metres beyond the threshold instead of the usual 300 (correct me if I'm wrong), but clearly above the 767's wake and still with lots of free rwy in front for deceleration

My question to ATCs and to captains & F/Os of small airplanes here...

Could pilots of small aircraft take such a decision, or be allowed to do so, or even be warned to act this way in order to avoid situations like the one described? At a peak hour, would not be better to land a little forward than incorporate an airplane to the landing queue for 2nd time? For sure RJs, ATRS, SAABs, (and even M82s or 733s/735s behind 744s or future 380s) have enough lenght left for deceleration even if they touch down 100 or 200 m. further.
BCN's 25/07 is not one of the longest rwys, but 738s, 757s, 321s and even 300s and 762s clear it by half the length after landing.

Waht do you think?

Best turbulences

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: Trickijedi
Posted 2002-08-20 20:38:21 and read 2908 times.

I'va had a smimilar experience but not quire as dramamtic. Thia happended on my way home from MSP to ORD. The weather was absolutely horrendous... a thunderstorm had just passed and there were very heavy clouds all throughout and was generally a turbulent ride all the way down to final approach. As a result of the poor weather, both MSP and ORD were closed for a few hours earlier in the day. So needless to say, ATC had their hands full clearing twice the load of planes to land and takeoff. We were scheduled to land on 9R (I was listening in on United's Channel 9), everything was fine and thought we were going to land until the very last minute the flaps and the landing gears go back up and all of our heads are pushed back against the headrest. It turns out that we were too close to a 757 ahead of us landing on the same runway. We felt the plane shake a little but I wasn't sure if it was the result of the wake turbulance or the engine power on the go-around. As the pilot put it: "They packed us all in on the approach". We went back around and were the only plane to land on Rwy 4 with no one in front of us.

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: Rick767
Posted 2002-08-20 20:41:59 and read 2906 times.

Dragonrapide,

"If the 'box' of another airplane enters the 'box' of the first one, would this be a near miss?"

No it wouldn't. Erasmus was right this was not a "near miss". It is not uncommon for wake turbulence from 757/767 aircraft to last several minutes in certain conditions. The turn of the aircraft would have been initiated by ATC to route the aircraft safely away from other departing / arriving traffic.

Officially a what you consider to be a "near miss" is termed an "Airprox". An airprox is when a loss of standard separation between aircraft occurs. No Airprox occured in this case.

There are various levels of Airprox reports:

Airprox "C" - A loss of separation occured, but no risk of collision existed
Airprox "B" - A loss of separation occured, and the safety of the aircraft was compromised
Airprox "A" - A loss of separation occured, and an actual risk of collision existed

Thankfully most airproxes are Airprox "C"s. During 2001 in the UK 78% of total Airprox reports were "C" cases (82 total reports).

Hope this was of interest. Remember though, an airprox never happened here, the Captain just made a (correct) decision to discontinue the approach.

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: Sabena 690
Posted 2002-08-20 20:51:34 and read 2883 times.

Interesting story!

How was your SNBA experience?

Regards,
Frederic

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: Apuneger
Posted 2002-08-20 23:03:57 and read 2812 times.

Dragonrapide:

You're probably right about ATC asking your aircraft to discontinue the approach to LHR. Well, even if the captain just decided to discontinue the approach as Rick767 says,...what was I trying to say now?...Oh well,it really doesn't matter anymore...

Anyway, nice to see you admit that your thread title was - maybe- a little bit too dramatic. I respect that a lot! At least you're not one of those guys that tends to get quite angry when people have some sort of criticism on their writings. If only all forum users were like you  Smile/happy/getting dizzy

Rick767

Thanks for your excellent comment on this situation. You know, thanks to your, and other skilled people's comments, I learn a lot just by reading interesting threads on this forum, every single day...

Greetz,

Ivan

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: Rick767
Posted 2002-08-20 23:50:38 and read 2780 times.

Just as a sidenote here with a BAe 146 / RJ100 (classed in the UK as a "Lower Medium" aircraft) following a 767 (classed of course as a "Heavy" aircraft) the minimum recommended spacing on the approach is 5 miles.

ATC will always try to acheive the correct spacing between arriving traffic. However, sometimes it just doesn't work out. If the RJ100 was less than 5 miles behind the 767, ATC would have informed the pilot of the RJ, and asked him if he was willing to continue with a spacing lower than the CAA recommend.

For example, I was flying into Gatwick in a 757 last week behind a Virgin Atlantic 747. Spacing on the approach was tight, and we had already been in a holding pattern for about 10 minutes. We were informed by the controller that we were following a 747, 3 miles ahead on the approach, with a recommended spacing of 5 miles, and he asked if we were "happy to continue".

We said yes, we usually do in this case. I have landed with 3 mile spacing in a 757 behind a 747 several times and it has never been a problem. But one thing is certain, the responsibility for getting flipped over by wake turbulence was then all ours. ATC had washed their hands of that scenario. If at 700ft above the ground we started to enter heavy wake, in all likelyhood we would go-around immediately.

My best guess is that the scenario above happened to the RJ100 crew. Maybe they did have the recommended spacing, who knows? Like I said wake voritces can remain much longer than usual in certain atmospheric conditions. Don't ask me what they are, I don't know. As far as I am aware even scientists don't really understand what causes them to be so prolonged in rare cases.

Anyway it was just something else that popped into my head on this one!

Apuneger,

Hey that's what these forums are all about. Usually I learn something new on here every day too. That's one great thing about this industry, which even those who have been in it 25 years will tell you, you never stop learning.

Cheers,

Rick.

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: Turbulence
Posted 2002-08-21 17:16:07 and read 2649 times.

Rick767,

I see in your post an answer to my comment, too, which I thank you. But I insist in my basic idea: small airplane flaring slightly higher than the precedent heavy.
Could/should/would this happen, either on own decision or directed by ATC?

Thank you again.

Best turbulences

Thank you again

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: Com3205
Posted 2002-08-21 21:16:54 and read 2583 times.

Turbulence
If the wind is in the RWY or calm and you're following a heavy you can just stay above the wake by taking half a dot above the glideslope on the ILS, we do it with the A32F and B737 so it's certainly no problem with a BAe. It's even so that if you come in high and aim for the correct touchdown point your roll out distance will be less than on a standard 3° glide because of less flare. (you better trained it before you have a go).
I always keep an eye on the TCAS so you can see if the previous one is slowing down and ATC is not telling you (BRU). Just keeping separation myself.
Anyway a go around was probably a good idea.

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: EGGD
Posted 2002-08-21 23:58:25 and read 2506 times.

Fly into LHR at 7am and you will understand the meaning of 'near miss'

Dan  Smile

Topic: RE: I Experienced A Near Miss With Snba To LHR
Username: Turbulence
Posted 2002-08-22 17:23:31 and read 2393 times.

Com3205,

That was exactly my idea, and you explained it the best easiest way you could, very graphically. This is just what I meant, and was just wondering if everyone can do it.

Thanks a lot.

Best turbulences


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