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punkalouver
20th Oct 2005, 02:00
Letter to the editor at Aviation Week.

".....when I was in the Air Force, at every strategic Air command base that I was stationed, the runways were equipped with a simple aircraft arrest system. It consisted of two huge anchor chains on both sides of the runway connected by a spring loaded arrest wire lying across the runway that was triggered by the tower if controllers saw a potential overrun problem. It worked for B-52's and would have saved that Air France A-340."

Are these still in operation and is there any application in the civilian world?

4Greens
20th Oct 2005, 02:35
We had them at Naval airstations and I know they work because I used one once. It does help to have a hook.

Argus
20th Oct 2005, 02:48
At RN air stations there were two types, each of which had a raised wire or two stretched across the runway at the upwind end. One was called CHAG (Chain Arrester Gear) because the inertia was a lengthy and heavy piece of chain on each side of the runway. The other was SPRAG (Spray Arrester Gear) which boasted a more sophisticated hydraulic arrangement with a piston and a water filled cylinder.

I can confirm that they were very effective for both aircrew and hook fitted aircraft. Not so sure about a Buff though...

Airbubba
20th Oct 2005, 02:54
A grooved runway would have probably saved AF as well but that is still a novel concept in countries like Canada and India.

Flight Detent
20th Oct 2005, 03:12
Guys,

My understanding is that the AF A-340 didn't go off the end of the runway, it speared off to the side at some point!

Just a minor point!

Cheers, FD :hmm:

ICT_SLB
20th Oct 2005, 04:34
Another problem with arrestor gear is that it does a real number on AHRS (Compass) systems with all that iron just at the runway end. Remnant sets are causing ATC problems at Chicago O'Hare - AHRS equiped aircraft don't follow the same heading as ones with IRS.

We had a similar problem on the end of our company runway (left over from F-104 production) - measured over 6 degrees variation in Mag Heading as you moved towards the gear.

ORAC
20th Oct 2005, 08:04
There are a variety of systems, CHAG, RHAG, PUAG etc. They similarity of all of them is that aircraft have to trample the cable when itīs down and have an arrestor hook to engage it when itīs up. The expense of modifying all aircraft to trample them safely would be high. The fitting of a hook to a civil aircraft in terms of structure, weight penalty and drag would be unacceptable. (Only FJs, only then only some, have hooks. Large aircraft such as C-130, B-52 etc do not).

The other method used is the Barrier, where a large net (think supersize tennis net) is swung up and the aircraft is dragged to a stop. This is practicable up to certain weights, but I believe (though am willing to be contradicted) that the mass/inertia of an airliner, again, make it inpracticable. As would the problems of locating it before approach lights etc.

Gravel (or similar) overrun beds have been mooted and might be suitable in some cases. But, as stated, would be of moot use unless the aircraft went of the end of the runway in a straight line........

wobble2plank
20th Oct 2005, 08:37
The other snag with hook arrestor systems is the required moification to the airframe to prevent it being ripped in two by the decelleration.

The system has to be tuneable to the landing weight of the aircraft to provide the 'correct' resistance. Have a look at a few old vids from carrier deck landings where the arrestor gear was set for the wrong aircraft!

There is no point in preventing runway overrun damage when you pull the tail off!:p

N380UA
20th Oct 2005, 08:42
I don’t think that a wire would or could do the job. Take the max landing weight of a 743 of about 255 tons met. and add the pax martini factor all of which is coming to a stop within a few feet; that just might make matters worst. A bunch of airports has installed arrestor beds rather then wires. Some are made of natural material some have porous concrete. Either way the results and effects are the same. More often then not one can reuse the aircraft, pax walk of health- if even a bit through the wind, and the costs are "minimal".

Here is an interesting article I found on the net.


On Saturday, May 8, at JFK International Airport, a soft ground arrestor system developed by the Federal Aviation Administration safely stopped an American Eagle Saab 340, carrying 27 passengers and 3 crew, from possibly plunging off the end of the runway into Thurston Bay. The FAA developed and tested the arrestor system at the Tech Center and installed it at JFK under cooperative research and development agreements with Engineered Systems (ESCO) of Lester, PA, and the Port Authority of New York and New Jersey. According to preliminary reports, the aircraft, arriving in fog and light rain, landed long on runway 4 Right. It landed just 1,500 ft. from the end of the runway- 500 ft. beyond which is Thurston Bay. The aircraft
stopped 248 feet into the 400- foot long arrestor bed. All 30 onboard walked off the aircraft. Damage to the aircraft was minimal -- one bent prop and a couple of blown tires. All landing gear remained intact. The National Transportation Safety Board (NTSB) is now gathering data from the flight data recorder, which will give the aircraft’s exit velocity, enabling investigators to recreate the incident. The arrestor bed, installed in 1997, is constructed of
cellular concrete and is designed to bring transport aircraft to a safe stop in the unlikely event of a runway overrun. The cost to install the bed at JFK was approximately $2,620,000. Damage to the bed was restricted to a 30-foot wide and 250-foot long section. ESCO began repairs on Monday morning, May 11. The genesis for the development of an arrestor bed came in 1984 when a DC-10 aircraft overshot runway 4 Right at JFK and plunged into the bay. Although no serious personal injuries occurred, the incident resulted in $30 million in damages and prompted the NSTB to issue a safety recommendation to the FAA to ascertain whether an arresting system was feasible. The Port Authority has installed a second arrestor bed at LaGuardia Airport, and is in the process of installing a second system at that airport. The FAA has issued an advisory circular to provide guidance on the design of engineered arrestor systems, using knowledge gained from the design, installation, and monitoring of the JFK system

Sleeve Wing
20th Oct 2005, 08:50
ORAC.

>There are a variety of systems, CHAG, RHAG, PUAG etc. They similarity of all of them is that aircraft have to trample the cable when itīs down and have an arrestor hook to engage it when itīs up. <

I agree with your view.

IIRC, in the nineties, Heraklion had a couple of arrester systems for the Mirages based there.
We had to adjust RTOWs dependent on the system that was rigged because of appreciable restrictions to TODA. This often caused a lot of problems with available fuel for longish sectors.

We were only allowed to "trample", as a last resort, if we needed to cross, taxiing, after landing.

Good idea but too many problems.

:ok:

Rgds, Sleeve.

Clockwork Mouse
20th Oct 2005, 08:56
What would you charge it with?

Argus
20th Oct 2005, 09:35
Thanks Orac. Old men forget.

Back in the halcyon days of the FAA (and when Lossie was the jewel in the crown of naval aviation), the front line hook equipped naval aircraft then in service (i.e. F4, Buccaneer, Vixen, Gannet) were designed for deck arrested landings. Ergo wire engagements weren't usually a problem.

These aircraft were also able to trample the raised wires at the upwind end of the runway, as could the Hunter T8 and GA11 then in naval service. Not so the visiting Lightnings, Gnats, F104s, F5s and F105s, who always had to backtrack after landing.

There was always speculation about the ability of the hook equipped Hunter T8 and GA11 to withstand a wire engagement at speed. I saw a T8 engage the CHAG at Mill Town (the Lossie satellite) in the late 60s, after a 'flame out' returning from Rosehearty Range. After a perfect glide, the aircraft survived. Unfortunately, the pilot didn't, as he used the seat on the ground outside of the ground level/90 knots envelope.

Schiller
20th Oct 2005, 17:54
The stresses on aircraft engaging the SPRAG, GHAG or whatever wasn't the same as for a deck landing since the gear was (is?) at the upwind end and hence the engagement would normally be at a much slower speed. However, a Hunter (can't remember whether T8 or GA11) did inadvertently pick up a retracted wire at the downwind end of the runway while landing with a rather too high nose up attitude at Lossie one night. The pilot came to a very surprised halt but I seem to remember that the aircraft was not seriously overstressed.

Doors to Automatic
21st Oct 2005, 16:56
Just out of interest; if the arrestor bed is used does the airport charge the airline?

Otherwise what would the financial incentive for the airport be of incurring the cost of the bed when any damage caused by an overrun would be paid for by the airline?

jammydonut
21st Oct 2005, 17:13
Arrested development of a major disaster could be a reason:confused:

VC10 Rib22
21st Oct 2005, 18:14
As N38OUA mentioned, there are various types of arrestor beds which stop aircraft in a remarkably short distance. Although the initial cost is considerable it must be balanced against the cost of an airframe and, more importantly, human life. They have a considerable lifespan and when an accident does occur, only the affected section is replaced, thus reducing cost, with negligible effect on stopping performance.

I would like to see them at most airports, certainly all major ones, but this wont happen until further incidents/accidents occur, such as Air France, Toronto, and the media decide to make it their "cause of the moment". The following links show some great pictures of the many different airports that have these facilities, mainly American, and the company involved are called ESCO.

http://www.panynj.gov/AboutthePortAuthority/PressCenter/images/emas_photo.JPG

www.esco-usa.com/com/instal.html

VC10 Rib22
:ok:

sikeano
21st Oct 2005, 22:59
they have one in uk and gosh we have a name for it
it is called FENCE
it is right at the end of the runway in lhr prevents planes from going into the parking area by mistake called m25 as it is full

VC10 Rib22
6th Nov 2005, 07:17
The Nov/Dec 2005 issue of 'airports of the world' has a feature on safety measures to prevent overruns, including the EMAS.

VC10 Rib22

:ok:

wiggy
6th Nov 2005, 09:25
Hi Schiller

FWIW the Approach end (or "downwind") cable often was used by aircraft such as the F-4, either following hydraulic problems or landing on a flooded runway - then again the F-4 was designed for such "abuse".

As I recall it the runway at Stanley ( Falklands) in the early 80's had 5 ( I think) cables, two at either end and one at the miodpoint and approach end engagements were the done thing.......it didn't always go as planned however, there was the F-4 that lost it's entire back end due to cable "whip".....anyone here care to own up?

ORAC
6th Nov 2005, 09:33
Going back to Schiller's point about approach end engagements, they can be planned for FJs with problems such as hydraulic problems where nosewheel steering is lost. Normally means a reduced landing speed though. The problem is the accidental ones, particularly into a barrier....

Durin 1991, at Tabuk, Saudi ATC cleverly left the barrier up when they changed runways during night operations. An RAF GR1, during a night landing, engaged it during the flare and whiplashed into the ground, broke her back, ran off the runway and caught fire. The crew, thankfully, managed to eject with minor injuries. The aircraft, ZA446, was classified as CAT4 and shipped home. crash photo (http://www.tornado-data.com/images/Mishaps/ZA466/Tornado%20Crash1.jpg)

Not sure if it ever flew again, but this (http://www.tornado-data.com/images/scrap/ZA466a.jpg) is all that's left of her now.