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-   -   Syria A320 mid air collision (https://www.pprune.org/rumours-news/496452-syria-a320-mid-air-collision.html)

TBSC 2nd Oct 2012 14:26

Other than it's full of incorrect information and guesses from news reports?

Lonewolf_50 2nd Oct 2012 15:46

hedgehopper, I seem to recall that there was a media report about this a week or so back, which led with the helicopter going down.

ZeBedie 2nd Oct 2012 16:16

The lower slice in the rudder/fin was obviously done from behind. I guess that's plausible, since rotor tip speed would be higher than the 350kts TAS of the A320. But on the other hand, wouldn't the rotor have lost the majority of it's energy with the first strike - the one that went right through?

Passenger 389 2nd Oct 2012 16:59


hedgehopper, I seem to recall that there was a media report about this a week or so back, which led with the helicopter going down.
Lonewolf_50 is correct. The following is from an article that was published on the Voice of America website on September 20, 2012:

"Syrian state television says a military helicopter that crashed near Damascus clipped the tail of a Syrian passenger plane in midair. The report said the passenger jet landed safely Thursday at Damascus International Airport with 200 people onboard."

"Opposition activists said rebels shot down the helicopter. Fighters opposed to Syrian President Bashar al-Assad have claimed to have downed military helicopters before, including late last month in Damascus."

"The Syrian state report did not include eye witnesses to the alleged incident."

sandos 3rd Oct 2012 20:23


Originally Posted by ZeBedie (Post 7445304)
The lower slice in the rudder/fin was obviously done from behind. I guess that's plausible, since rotor tip speed would be higher than the 350kts TAS of the A320. But on the other hand, wouldn't the rotor have lost the majority of it's energy with the first strike - the one that went right through?

I think you slightly underestimate the power in the main rotor: https://www.youtube.com/watch?v=vm398hEzH8E

Notice how the rotation does not stop even when impacting the ground. I only fly RC helos, albeit with totally different weight ratios but I do have respect for flying blenders of every size above ~60 cm. Also, does it really take that much energy to cut through a light-weight aircraft structure? Its not exactly steel/concrete.

Roger Greendeck 3rd Oct 2012 22:48

Main rotor energy is substantial and it wont stop on first impact when it hits anything. If the object s robust enought the blade/hub assembly may shatter or depart the head BT the following blades will keep coming at pretty much the same speed. Whilst I can't comment on the veracity of this particular story the impact marks on the tail are consistent with a mid air strike I have seen.

HAWK21M 4th Oct 2012 09:18

What does TCAS say on both Aircraft......

Lonewolf_50 4th Oct 2012 12:41

Hawk, why do you assume that there is TCAS in a helicopter?

BobnSpike 4th Oct 2012 13:06

...or that it would be on in an active anti-air environment

Herod 4th Oct 2012 16:46

If the heli was shot down by the rebels, what sort of missile homing system would they have? Seems to me that having heat-seeking missiles fired off anywhere near an airliner is a bad idea.

rcsa 4th Oct 2012 17:43

Herod
 
We believe the helo was not shot down by rebels. It was avoiding being shot down when it collided with the A320.

Which ultimately had the same effect as being shot down.

The FSA and other rebel units may have MANPAD heat-seeking AA systems, but most of the reporting has had them firing AAA (mostly 20mm) in the general direction of ASA aircraft. Any hits have been more by luck than judgement.

Others have noted there would likely be no TCAS in a military helicopter flying a combat mission.

Even if the A320 crew knew they were in danger of a collision, they would have had little or no idea what they were trying to avoid, where it was coming from, how fast it was going, or how to avoid it.

Good luck + good airmanship + some more good luck.

Tourist 7th Oct 2012 15:18

"Is it not supposed to be a forum for pilots?"


"but I guess it may have begun a fast descent"


Hmm.

1. Exactly how fast do you think a helicopter such as a Hip can descend?

2. Exactly how high above terrain do you think this sort of move generally begins?

Lonewolf_50 10th Oct 2012 13:56

Helicopter autorotative descent: would need to take a peak at the Hip's flight manual, but I'd guess 3-5000 FPM is in the ball park. ;)

As to "height above terrain" this story makes me scratch my head a bit. Helicopter up at 12K is an altitude that must have been chosen for a purpose. With Damascus roughly 2200 feet above MSL, that's still about 10K AGL ... which leads me to guess that this flight profile was chosen to avoid small arms fire. (I may be wrong.)

But it got hit anyway? Seems to me that some actual AAA like a 57mm might be involved if that were the case.

Ran into another plane because neither cockpit crew saw one another? Most likely explanation from where I sit.

A lot I don't "get" about this one.

Tourist 11th Oct 2012 08:28

Lonewolf

No, as with just about all helicopters, 2500-3000ftpm is more realistic, to descend faster you would either need high angle of bank, or a temporary dive, and neither would give a straight cut.


High speed descents are a small arms fire procedure, so usually start approx 2000ft agl as that is the threat zone. There is no point whatsoever in starting the dirty dive at 10000ft agl. The dive can only go on for a little while in a helicopter before vmax at which point you are stabilised at a low rate of descent again.

I speak as one of the few( only ) people on here to fly both types of aircraft involved.

wild goose 11th Oct 2012 22:59

What if the A320 had been on the ground and the Hip struck it whilst maneuvering too close - say - at night or otherwise?
The Syrian propaganda machine can't be trusted for the decent truth - anything threatening their public can be expected to be altered in the news.

The Hip wouldn't have TCAS but it has a transponder (IFF).
Regarding an earlier post here - the rebels dont have aircraft
If they tried to operate them, they would be blasted out of the sky in an instant.
Also, the rebels dont have SSR to pick up a transponder/IFF. At best they may have 57mm but in all likelihood its light AAA like 23mm or 14.5mm.

Lonewolf_50 15th Oct 2012 14:16

Tourist: your response was only in part to what I commented upon. The rest you seem to be thinking out loud.

No, as with just about all helicopters, 2500-3000ftpm is more realistic, to descend faster you would either need high angle of bank, or a temporary dive, and neither would give a straight cut.
"Just about all helicopters?"
Not going down that rat hole, but I'll accept I may have been a bit high on the ball park. As I've not flown any Mi I'll take your word for it.

How fast you descend depends on how fast you want to fall, if you fly max glide or max range auto, if you slip, gross weight of the helo, density altitude ... but you know most of that.

High speed descents are a small arms fire procedure, so usually start approx 2000ft agl as that is the threat zone. There is no point whatsoever in starting the dirty dive at 10000ft agl.
Agreed, from my own experience, apart from the fact that I never suggested a "dive" dirty or otherwise.

What I was talking about was that he may have been flying that high to AVOID small arms fire.

The dive can only go on for a little while in a helicopter before vmax at which point you are stabilised at a low rate of descent again.
Dive? Anyone who has flown military helicopters knows the limitations of the airframe in regards to missile avoidance maneuvers. And small arms fire avoidance maneuvers. You seem to be using "dive" where I did not.

Are we even having the same conversation?

There is a max airspeed that you limit yourself to in order to avoid retreating blade stall, if you know your aircraft. That does not preclude a high speed descent, nor an autorotative descent. FWIW, I'd suggest you

1. Try not to teach your grandmother to suck eggs, and
2. remember that I know how to fly helicopters.
3. See above comment on why the helicopter may have been up that high.


I speak as one of the few( only ) people on here to fly both types of aircraft involved.
Cheers.

Had you understood my point about high altitude to avoid small arms fire, you'd most likely not have responded as you did.

Tourist 17th Oct 2012 22:11

Not teaching you to suck eggs lonewolf, but small arms threat zone is 2000ft. 10000 and up is certainly not "small arms"
territory.

Lonewolf_50 18th Oct 2012 15:20

I see that you have missed the point yet again.
Not wasting further time.

Take care, fly safe.

Abu Ali 2nd Mar 2013 21:40

I was on this flight.
 
Hello all,

I was on this flight and indeed know that we were very lucky.

I'm reading all your comments with great interest because I'm trying to understand the technical side of the incident, as a non-technical person.

I'd like to combine my first-hand experience with your technical knowledge in order to have a more complete picture, and would be open to answer any questions.

JammedStab 3rd Mar 2013 10:15


Originally Posted by Abu Ali (Post 7722924)
Hello all,

I was on this flight and indeed know that we were very lucky.

I'm reading all your comments with great interest because I'm trying to understand the technical side of the incident, as a non-technical person.

I'd like to combine my first-hand experience with your technical knowledge in order to have a more complete picture, and would be open to answer any questions.

Thank you,

Just tell us what your experience was. From where you were sitting, what you felt, saw and heard. Time of day. How the aircraft flew after the collision. The reaction of the flight crew and flight attendants. Preparation for emergency landing etc.


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