Descent speed in migration season

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ahramin
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Descent speed in migration season

Post by ahramin »

Do you reduce your descent speed for birds in migratory seasons? At what altitude do you start slowing down? What speed do you slow down to?
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Post by CPS1 »

I've only had one bird strike, actually is was a flock of small birds that happen to fly in front of me as I was landing at the Earlton Ontario airport in a King Air 100. No damage just a bunch of smears. Icky.

I know a guy that hit a goose while in cruise at night. That would certainly wake you up ! I'm sure you could minimize damage to your aircraft if you slow down as you make your approach to an airport but have no Idea at what altitude Geese fly at while in cruise.

I almost hit a bunch of baloons (Clown type) at 10,000 Feet over downtown T.O. I was doing about 215 Kts. It was so close that I actually ducked my head as they went by.
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Post by oldtimer »

I reduce to 308 kts passing 14,000. That is a Lear 25 limitation, supposedly for bird strike protection.

I don't think reduced airspeed will have as much affect. you are travelling too fast to see and avoid. Operating with the airborne radar and ever light you own on is better. The worst place to take a bird is in the windshield. Most engines and wings should survive all but the largest birds. Tail feathers are a bit more suseptable to severe damage but the windshield can be a killer. You are better protected with the windshield heat on because a glass windshield is 5 times stronger when heated than a cold windshields. I have hit seagulls in a Cheyenne at 120 kts on take-off and at 220 kts on descent and it matters more where you hit them than how fast you are going. Damage appeared about the same. Years ago a goose struck our Learjet in the horizontal stab and the airplane had to be ferried to the USA for repairs. This happened at 02:00 in the morning. Darker that all getout. Smucked a bunch of seagulls in the Gulfstream doing 290 kts and it just made a big mess. No damage at all. Hit them a glancing blow with the engine cowling. Also knew a cropsprayer who was almost killed when the hit a duck in the windshied of a Super Cub.
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Post by Bcn-In-Bnd »

The last good bird strike I saw was a kingair that hit a duck (they think) The damege to the leading edge was bad enough to cause a fludder in the ailerons. :?
AND yes I slow down and my lights and windshield-heat are on as well.
I just tried to do a google search for pictures of a 737 that hit docks climbing out of 6-7000 feet (i think)
Anyway the the birds came through the nose and moved the capt. instruments into his lap. It looked like lots of fun. :|
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Post by Panama Jack »

Supposedly, this is a reason why the FAA has regulated (amongst other reasons) a maximum speed of 250 KIAS below 10,000 feet, and Transport Canada has recommended the same in lieu of a high speed climb below 10,000 (which is legal here in Canada).

Some aircraft's Vmo's are restricted for bird strike protection, however, it corresponds to a certain weight limit for a bird-- if you hit a swan it might end up in your lap. Yes, definately, I'd prefer a bird hitting ANY part of the aircraft over the cockpit windows.

I've heard two techniques for reducing the risk of birdstrikes (besides certain speed restrictions)-- one being "Landing Lights- on" (this makes it look like the big flying thing has eyes and is hungry) and "Weather Radar- on" where I have been told that the radar scrambles the birds' brains and they don't like that, so they clear a path.

I buy into the Landing Lights on theory, but I am wondering whether the effect of weather radar is just an old wive's tale? Any scientific backup? (please-- no "when I'm flying and have the WX radar on the birds get out of my way")
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Post by co-joe »

...the radar scrambles the birds' brains and they don't like that, so they clear a path
That's not the only thing that gets scrambled. Come to think of it, a couple of impotent shit-hawks isn't such a bad thing. :D
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Post by Bcn-In-Bnd »

"Weather Radar- on"
I have read or seen this before.
I dont have any scientific backup, but what the hell turn the thing on.
Maybe it stops the birds maybe it dosnt. :?
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Post by Aviation's Golden Boy »

Bcn-In-Bnd wrote:I just tried to do a google search for pictures of a 737 that hit docks climbing out of 6-7000 feet (i think)
Actually, since 737's have really never been adapted well to float flying, you'll generally find very few incidences of 37's hitting docks; especially at 6-7000 feet.
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Post by oldtimer »

The radar thing is using the SWAG method of reasoning. A Scientific Wild Ass Guess. But I did read where airlines (name escapes me, Air Canada comes to mind ) and the CF at Cold Lake have done some studies on bird strikes and it APPEARS that radar energy is, in some cases, detectable by some birds.
In very old radars, the Magnetron is the weak link and it deterioates with age and use. According to Archie Trammel, the acnowledged guru of airborne radar, the magnetron in newer radars will last 10 years if you use it sparingly but if you use it continually, it will only last 10 years. the unit will deterioate at a constant rate, used or not. Latest generation radar is designed for constant use and in fact may not have an off switch.
so if it works, fine, if it doesn't, no harm done.

In my humble opinion, the 250 kts below 10,00 is an ATC flow control tool more than a bird strike thing but it is still probabilly a good idea. In the same vein, 308 kts below 14,000 is definatly a windshield bird strike limitation in the Lear. The Gulfstream had a bird protection limitation plus a performance penalty with windshield heat off. (235 Kts and max 2000 fpm descent) I still believe that slowing down will not help unless you slow to something ridiculous like 120kts. The time to slow down is when you have hit something. A better tact in my opinion is to be very vigilant during migration season in the bird corridors so read your CFS/AIP.
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Post by KAG »

here's some pics of birdstrikes....pretty nasty
http://wildlife.pr.erau.edu/Pictures3.htm
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Post by RB211 »

Speed is a big factor when it comes to bird strikes;

A precise calculation of the impact force on the aircraft includes the weight of bird, impact speed, dimensions and configuration of the bird, bird density and the angle of impact. Expressed in an equation, impact force will be proportional to the mass of the bird and the square of the impact speed. Applying realistic figures, a 4 lb bird striking an aircraft traveling at 250 kts results in an impact force of approximately 38,000 lbs. At an airspeed of 400 kts, the force increases to 100,000 lbs.

This is from a TC site on the subject:
http://www.tc.gc.ca/CivilAviation/Aerod ... 9/menu.htm

I believe the FAA tested an increased airspeed below 10,000 ft of 300 kts a few years ago. During that period a 727 struck a flock of birds at high speed and suffered very significant damage. It was determined the extent of the damage was directly related to the speed. The high speed experiment was ended.

Less speed may not stop you from hitting the birds but will certainly reduce the resulting damage.
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Post by Panama Jack »

Here is an interesting post from "Canukbirdstrike" on PPRUNE:
To all:

I spent over two years researching many issues with respect to bird strikes for a book publised by Transport Canada called Sharing the Skies. The issue of using weather radar as a means to warn birds is urban legend and most likely stems from some of the early air force weapons radar systems that were of much higher power levels than modern weather radar.

"Sharing the Skies" can be viewed on line at the Transport Canada website
http://www.tc.gc.ca/CivilAviation/A...p13549/menu.htm

Richard Sowden A320 Driver and part time bird strike researcher
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Post by Kurwa »

All the radar will do is sterilize the male bird's gonads and cause a slight decrease in the bird population reproductive rate.

Does the data on the impact force in relation to airspeed take into account the impact trajectory? Perhaps with a pointier aircraft the bird will just 'glance' off!

Those are great pics by the way, almost as good as those from the BC gov't med kingair that disassembled a deer on the runway!
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Post by Panama Jack »

More good revelations here:

http://www.pprune.org/forums/showthread ... did=132117
It is very true that exposure to electromagnetic engergy is not very good for living beings.

The abillity of wx radar to have any effect on brids at any appriciable distance i find hard to belive. The rules that we adhear to while ground testing the wx radar system are that no one should be infront of the radome or to the side, the Max permissable exposure level to microwave energy is a field strength of 10 milliwats per square centimeter. FAA AC 20-68B

On our Bendix RDR-4B the exposure minimum boundary is 14ft from the scanner. Further than that the field strenght has reduced.

Older A/C have older wx radars and these can be more powerful.
Aircraft weather radar has absolutely no demonstrated effect on birds. There have been several reviews/studies of this, plus analysis of bird sensory systems and they just can't sense the EMP at the low power that is emitted by aircraft radar.

Similar studies on lights were "inconclusive". Caged birds had absolutely minimal reactions to strobe lights.

As for the anectdotal information of turning on the radar while taxying and the birds move, I will respectfully say that it is more related to the noise and movement of the aircraft that causes the birds to move.

However, if it makes you feel good, turn on the radar!

The most effective bird strike mitigation tools are:

1. On the airport: An effective wildlife management program supported by pilots reporting bird activity to ATC.

2. In the air: Below 10,000 feet, keep the speed to 250 knots or less - aircraft and engines are not certified for the impact of larger birds at speeds above 250 knots and the data clearly shows that if you are going to hit anything at higher altitudes it will be waterfowl and raptors.

3. Report all bird strikes - to ATC as soon as possible and to the state authority. The data is invaluable for tracking down problems.
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Post by TTJJ »

As to the B-737-200, You only have to reduce speed to 250 below 10,000ft (or to 250 higher than 10,000 if migratory birds are a factor) IF you have lost your Window Heat. The Window Heat keeps the window more flexable so that it can absorb a bird impact at any speed.
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