GCA B377
I presume you're talking about a talkdown which has electronic glidepath information displayed to the controller because not all 'GCAs' (a generic term which might include radar or D/F) have glidepath guidance.
With PAR (Precision Approach Radar), initially a late reaction to the instruction 'begin descent NOW.......'
If the pilot continues to 'fly high', the controller will continually update the instructions to the pilot.
With PAR (Precision Approach Radar), initially a late reaction to the instruction 'begin descent NOW.......'
If the pilot continues to 'fly high', the controller will continually update the instructions to the pilot.
Last edited by chevvron; 25th Oct 2022 at 11:20.
Ah! The old non-precision GCA where the controller only had your position relative to the extended centre-line. "India 61, you are now 3 miles out and you should be passing through 1000 feet." Oops!
It was called an SRA; did my last one the day I retired Nov 31 2008; last PAR was 2001 when the thresholds for both runways had to be moved so the CR62 could no longer be used.
I remember flying with Americans as a new Flight Engineer on the Electra in 1990.
We were cleared for an SRA into Southend and it went somthing like this.
Controller: " Your range is X miles, commence your descent from xxxx ft. to maintain a 3 degree glide slope". Power is reduced a bit and we start down.
" :" Your range is now Y miles, your height should now be yyyy ft." we dive a bit and then level off.
" : "Your range is now Z miles, your height should now be zzzz ft." Captain says, " God damn, I wish he'd make his mind up what height he want's us at.
I say, "I think we better Go Around and start again". We do.
I then explain what an SRA is and explain the details on the JEPP plate. Captain says, "Like a PAR then but without radar knowing our height". Me only being a F/E say, "I think so", and we make a perfectly good second approach.
Lots more SRAs done into southend with the same crew and others and no more problems.
We were cleared for an SRA into Southend and it went somthing like this.
Controller: " Your range is X miles, commence your descent from xxxx ft. to maintain a 3 degree glide slope". Power is reduced a bit and we start down.
" :" Your range is now Y miles, your height should now be yyyy ft." we dive a bit and then level off.
" : "Your range is now Z miles, your height should now be zzzz ft." Captain says, " God damn, I wish he'd make his mind up what height he want's us at.
I say, "I think we better Go Around and start again". We do.
I then explain what an SRA is and explain the details on the JEPP plate. Captain says, "Like a PAR then but without radar knowing our height". Me only being a F/E say, "I think so", and we make a perfectly good second approach.
Lots more SRAs done into southend with the same crew and others and no more problems.
Watch the film Out of the Clouds and you can see James Roberston Justice fly a GCA radar talkdown in a Strat. I read the Prestwick crash report I notice that the glideslope angle was 3 1/2 degrees which is quite steep. The Strat approached in a nose down attitude and like the aircraft of the day full flap was extended once going visual. I flew Dart Herald and doing this involved a very positive forward push to stop the aircraft going back in the gloom when Land flap was selected. A Strat often landed nosewheel first and a positive rotation in the flare would have led to a stall. With the limited lighting and the previous history of the crew duty I find it hard to blame the crew.
I remember listening to a Navajo flying a PAR into Bedford and the two radar approaches are very different with much more guidance in the PAR.
I remember listening to a Navajo flying a PAR into Bedford and the two radar approaches are very different with much more guidance in the PAR.
Watch the film Out of the Clouds and you can see James Roberston Justice fly a GCA radar talkdown in a Strat. I read the Prestwick crash report I notice that the glideslope angle was 3 1/2 degrees which is quite steep. The Strat approached in a nose down attitude and like the aircraft of the day full flap was extended once going visual. I flew Dart Herald and doing this involved a very positive forward push to stop the aircraft going back in the gloom when Land flap was selected. A Strat often landed nosewheel first and a positive rotation in the flare would have led to a stall. With the limited lighting and the previous history of the crew duty I find it hard to blame the crew.
I remember listening to a Navajo flying a PAR into Bedford and the two radar approaches are very different with much more guidance in the PAR.
I remember listening to a Navajo flying a PAR into Bedford and the two radar approaches are very different with much more guidance in the PAR.
Technques vary with all types, for instance the BAC 1-11 would use flaps to initiate descent when intercepting the glidepath.
My point was that older aircraft only committed to land flap once visual contact had been established. The Herald went from 5 degrees to 30 and required a hefty push. The Strat had more flap settings but this technique of selecting flap very late destabilised the aircraft which due to the slope already had a high rate of descent.It is worth reading the link I posted a few days ago written by a Boac Strat pilot about how to land the aircraft
At my last employer anything over 3.5 degrees was considered as steep and we frequently flew approaches to airfields such as Marseille which has a 4 degree slope.
At my last employer anything over 3.5 degrees was considered as steep and we frequently flew approaches to airfields such as Marseille which has a 4 degree slope.
As regards SRAs, controllers are required to carry out at least one every 30 days in order to maintain competency jusy in case there is an ILS failure.
Was this to me?If so here it is-
http://www.ovi.ch/b377/articles/speedbird/index.html
http://www.ovi.ch/b377/articles/speedbird/index.html
The LCY operation required special aircraft certification. I note that currently SRA are not available at LGW, a consequence of the change in ATC provider?
Reading the report the Commander failed to maintain a descent rate to maintain the 3.5 degree approach slope. Upon going visual the aircraft sink rate then appears to increase whilst at the same time there is a change in aircraft configuration. This was in the days of pilots aiming for the threshold rather than 1000ft in as we do now. It would be a lot to process especially after having been on duty for a long time and having already flown one sector with an in-flight emergency. The swiss-cheese can be seen stacking up against them..
It is worth looking at why the Strat usually landed nosewheel first.The closest anyone came to answering this question correctly was the reference to the inboard wing spoilers mandated by the (US)CAA (one of the reasons the aircraft's entry into service was delayed for a year).They were mandated for the civilian operators right to the end of their service lives, including on the modified Super-Strats that PAA flew. They deployed whenever flaps were lowered 10 degrees or more, and the purpose was to deflect the airflow over the inboard portion of the wing where it met the fuselage where, unlike other aircraft types, Boeing had not added a fairing. Without the fairing any sudden changes in wing angle would disrupt airflow over the inboard wing causing a stall. Early pilots (including the CAA) quickly learned that if they attempted to flare the aircraft as they would in a Douglas or a Connie the 377 would drop like a rock onto the runway. Not exactly the thing to do with tired First Class passengers after a 9-hour flight. No amount of heaving back on the pole would induce the mainwheels to make contact first. Various explanations were offered for this peculiarity... Others pinned the blame on the pernicious lift-spoilers.
Why build a splendid wing and then fit lift spoilers? The story was that the Civil Aeronautics Administration (CAA: the FAA-to-be) would not give the type its Certificate of Airworthiness because a wing was apt to drop when the aircraft stalled. The CAA wanted the nose to drop first, and the only swift remedy was to destroy an area of lift near the fuselage.
Now imagine the situation where you have allowed a high rate of descent to develop close to the ground and the pilot gives a good heave on the stick to arrest the rate of descent. Was it a stall at low altitude that caused the crash?
Why build a splendid wing and then fit lift spoilers? The story was that the Civil Aeronautics Administration (CAA: the FAA-to-be) would not give the type its Certificate of Airworthiness because a wing was apt to drop when the aircraft stalled. The CAA wanted the nose to drop first, and the only swift remedy was to destroy an area of lift near the fuselage.
Now imagine the situation where you have allowed a high rate of descent to develop close to the ground and the pilot gives a good heave on the stick to arrest the rate of descent. Was it a stall at low altitude that caused the crash?
The change of provider at Gatwick (now reversed) had no effect because Gatwick Tower didn't provided SRAs; it's ony airfields with their own radar like Southampton, Southend, Bournemouth, Farnborough etc who provide them.
