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Airbus Double Flash Sequence: Improving Safety?  
User currently offlineglidepath73 From Germany, joined Mar 2005, 1021 posts, RR: 44
Posted (3 years 5 months 3 weeks 1 hour ago) and read 4284 times:

Hi all,

does the Airbus typical double flash sequence as shown in this video here improve air travel safety?

http://www.youtube.com/watch?v=Xpr5T0EC0_k


Does it help air traffic controllers to distinguish between Airbus and Boeing planes?

How about pilots? Does the double flash help them when departing or approaching airports?

Greetz,
Patrick


Aviation! That rocks...
14 replies: All unread, jump to last
 
User currently onlinehorstroad From Germany, joined Apr 2010, 284 posts, RR: 0
Reply 1, posted (3 years 5 months 3 weeks ago) and read 4209 times:

i guess it´s just an "airbus thing" to double flash.
ERJ also flash twice a second, but leading edge and trailing edge wingtip alternating.

i don´t think it is to distinguish the manufacturers, as this is completely irrelevant for the controllers.


User currently onlineB777LRF From Luxembourg, joined Nov 2008, 1465 posts, RR: 3
Reply 2, posted (3 years 5 months 3 weeks ago) and read 4113 times:

Nothing at all to do with controllers, but it is grounded in safety. It's about visual recognition at night by other aircraft, and tests have shown that a double-flash strobe is recognised faster and more often than a single flash. Simple as that.

It's not only Airbus using those strobes, it's a quite popular option on very many business jets as well. Can't recall if any of the other airline manufacturers (BCA, BBD, EMB, SUK etc.) are using single or double flash as standard, or if it's available as an option.



From receips and radials over straight pipes to big fans - been there, done that, got the hearing defects to prove
User currently offlinecloudboy From United States of America, joined Jan 2004, 855 posts, RR: 0
Reply 3, posted (3 years 5 months 3 weeks ago) and read 4061 times:

You see it on plice cruisers and other emergency vehicles as well.


"Six becoming three doesn't create more Americans that want to fly." -Adam Pilarski
User currently offlineglidepath73 From Germany, joined Mar 2005, 1021 posts, RR: 44
Reply 4, posted (3 years 5 months 2 weeks 6 days 23 hours ago) and read 3942 times:

The only big airliner I remember, was the MD-11 which had it as well....


Aviation! That rocks...
User currently offlineMYT332 From United Kingdom, joined Sep 2003, 9112 posts, RR: 70
Reply 5, posted (3 years 5 months 2 weeks 6 days 23 hours ago) and read 3828 times:

For the record the double flash is actually two seperate bulbs in each wing firing in sequence.

Or so I learnt here once.  



One Life, Live it.
User currently offlineSPREE34 From United States of America, joined Jun 2004, 2264 posts, RR: 9
Reply 6, posted (3 years 5 months 2 weeks 6 days 14 hours ago) and read 3568 times:

DC-10 is the first I saw it on, and that was 1972.


I don't understand everything I don't know about this.
User currently offlineAA737-823 From United States of America, joined Mar 2000, 5947 posts, RR: 11
Reply 7, posted (3 years 5 months 2 weeks 6 days 12 hours ago) and read 3525 times:

Some of the Gen-Av planes do three flashes... gets kinda annoying!

I'm not sure that it's two separate bulbs, either.... It could be, but the ones I've seen weren't.


User currently offlineSPREE34 From United States of America, joined Jun 2004, 2264 posts, RR: 9
Reply 8, posted (3 years 5 months 2 weeks 6 days 11 hours ago) and read 3505 times:

Quoting AA737-823 (Reply 7):
I'm not sure that it's two separate bulbs, either.... It could be, but the ones I've seen weren't.


You are correct. 1 bulb. By design, the first flash is highest intensity, the next 2 are at a lower intensity. The same system is found in some GA anti-collision strobe lights. (red beacon)



I don't understand everything I don't know about this.
User currently offlinewn700driver From , joined Dec 1969, posts, RR:
Reply 9, posted (3 years 5 months 2 weeks 6 days 11 hours ago) and read 3497 times:

Quoting glidepath73 (Reply 4):


The only big airliner I remember, was the MD-11 which had it as well...

DC-10, MD-10, & Super 80s do this too.

Quoting SPREE34 (Reply 8):

You are correct. 1 bulb. By design, the first flash is highest intensity, the next 2 are at a lower intensity. The same system is found in some GA anti-collision strobe lights. (red beacon)

It isn't so much by design, just that the capacitors haven't had time to fully charge up again between the first and second flashes, hence the first one being more intense.


User currently offlineSPREE34 From United States of America, joined Jun 2004, 2264 posts, RR: 9
Reply 10, posted (3 years 5 months 2 weeks 6 days 11 hours ago) and read 3484 times:

Quoting wn700driver (Reply 9):
Super 80s do this too.

It's an optical illusion on the 80. The forward facing strobe only fires once, yet fro some angles one can see the rearward strobe flash as well, giving the double flash impression. It's not intentional, and the forward and rearward are not sequenced. You'll see this on the E170/75 and 190/95 as well.

Quoting wn700driver (Reply 9):
It isn't so much by design

I understand the capacitor theory. Makes sense. I was told it's by design by a Wheelen rep. Something to do with involuntary eye movement and following movement. Whatever, I didn't sleep at Holiday Inn last night.



I don't understand everything I don't know about this.
User currently offlineshamrock137 From United States of America, joined Jul 2005, 167 posts, RR: 0
Reply 11, posted (3 years 5 months 2 weeks 6 days 11 hours ago) and read 3482 times:

Another aspect of the Airbus design is it makes it easier to tell which direction the aircraft is facing. The double flash is only in the forward facing wingtip strobes while the aft facing strobe is a single flash.


Time to spare? Go by air!
User currently offline747fan From United States of America, joined Jun 2007, 1190 posts, RR: 1
Reply 12, posted (3 years 5 months 2 weeks 6 days 6 hours ago) and read 3414 times:

I'm not sure about improved safety, but it definitely makes it easier at night to identify aircraft - I can almost always tell its an Airbus, or at least narrow it down among bigger aircraft to an Airbus or DC-10/MD-11.
But my guess as to why they have two strobes is due to redundancy. For example, the L-1011 had two different anti-collision lights/beacons on both the top & bottom of the fuselage - from what I've read this was for redundancy purposes. One of the strobes/beacons could be "MEL'ed." I suppose this is the same for the Airbus wingtip strobes. Interestingly, just like the L-1011, the A380 has 2 separate anti-collision strobes on the top & bottom of the fuselage (usually its just 1).

Quoting wn700driver (Reply 9):
The only big airliner I remember, was the MD-11 which had it as well...

DC-10, MD-10, & Super 80s do this too.

Indeed, except for the Super 80. Also I believe the L-1011 had double wingtip strobes. However, the earlier A300's (A300B2/B4) don't have the double flash sequence.
I'll add that most, if not all of Fed Ex's 727's have the double flash sequence - I'm guessing this was a modification FX did to these aircraft. Interestingly, I've noticed FX A306's/A310 that do NOT have the double strobes (its an interesting sequence where the strobes alternate between the left & right wing, much like the ERJ-145).


User currently offlinewn700driver From , joined Dec 1969, posts, RR:
Reply 13, posted (3 years 5 months 2 weeks 6 days 5 hours ago) and read 3385 times:

Quoting SPREE34 (Reply 10):

It's an optical illusion on the 80. The forward facing strobe only fires once, yet fro some angles one can see the rearward strobe flash as well, giving the double flash impression. It's not intentional, and the forward and rearward are not sequenced. You'll see this on the E170/75 and 190/95 as well.
Quoting 747fan (Reply 12):

Indeed, except for the Super 80.

Yeah, I was wrong about that. I took a closer look at those out on the ramp, they don't have it.

Quoting SPREE34 (Reply 10):

I understand the capacitor theory. Makes sense. I was told it's by design by a Wheelen rep. Something to do with involuntary eye movement and following movement. Whatever, I didn't sleep at Holiday Inn last night.

I don't see that it would be a mutually exclusive thing... I know capacitors definitely work that way, but it could still very well be that the sequence was also designed with that in mind instead of a longer sequence...

Quoting 747fan (Reply 12):

I'll add that most, if not all of Fed Ex's 727's have the double flash sequence - I'm guessing this was a modification FX did to these aircraft.

There's an FX that heads eastbound most nights from AFW, and passes over us at DFW, usually around AM2 or 3, and usually not more than about 3000 or 4000 agl... I have certainly noticed this as well...


User currently offlinenavion1217 From United States of America, joined Jul 2010, 19 posts, RR: 0
Reply 14, posted (3 years 5 months 2 weeks 6 days 3 hours ago) and read 3351 times:

For GA airplanes, Whelen had a "cometflash" strobe which would flash 3 or 4 times. I think the Pulselight on landing lights is a better thing. I wish all the motorcycles here in Daytona would have it.

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