Swiss Avro Greaser in LCY
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I'm pretty sure the 5.5 degree glideslope has nothing to do with "scatter", it is simply for noise abatement (as promised to local residents before the airport was allowed to go ahead), and to miss the rather tall buildings that would otherwise penetrate the lower surface of the approach cone.
It doesn't really matter anyway as far as flare/float is concerned, if you haven't touched down by the inset marker lights it's a mandatory go-around.
Did three years in and out of LCY in the 146, great fun mostly.
Did see one Aer Lingus that floated past the markers, eventually got it down and stopped less than a foot from the end with brakes smoking fiercely. They had to pull it back with ropes tied around the gear legs... fun times (except for the skipper who was crapping himself).
It doesn't really matter anyway as far as flare/float is concerned, if you haven't touched down by the inset marker lights it's a mandatory go-around.
Did three years in and out of LCY in the 146, great fun mostly.
Did see one Aer Lingus that floated past the markers, eventually got it down and stopped less than a foot from the end with brakes smoking fiercely. They had to pull it back with ropes tied around the gear legs... fun times (except for the skipper who was crapping himself).
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It doesn't really matter anyway as far as flare/float is concerned, if you haven't touched down by the inset marker lights it's a mandatory go-around.
If during the approach it appears that the touchdown will be beyond the lights then you have to go-arround.
Having completed the approach, if the flare causes a float then it is 100% up to the crew if they go-arround or continue with the landing.
If you do make an approach at the correct speed round-out / close throttles and then float past the lights, you could try a balked landing.
But.
If you hit the bridge or any other obstacle on the way out, you can not claim that the airport authority required you to make that balked landing it is a 100% crew decision at that stage.
Remember also that in many cockpits the lights are not visible after a certain point in the landing even if you hit the aiming markers exactly.
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Hmmm... well it was certainly a mandatory go-around in our company, and that was what was taught by the BAe instructors in the 146 sim... maybe it was different for other types. The point was that once past those lights, you have absolutely no assurance of being able to stop in the 146 or AVRO.
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my understanding is that the 5.5 degree slope on 28 is to bring the t/d point nearer to the easterly end of the asphalt, thereby providing additional lda and therefore higher landing weights... someone said geometry ? this would be the bottom line.
The history of LCY stems from the Dash 7, which because it could fly a 7.5 deg approach, this angle was chosen for noise abatement reasons. Actually a political rather than practical choice.
In consultation with the local authority and residents, the 146 operation should have been limited to 6 deg for noise and obstacle clearance reasons.
5.5 evolved as a better choice for aircraft handling. The obstacle problems on 10 were solved with a ‘cat2’ quality glide slope – enables reduce obstacle clearances, and there was some 'help' with building regulations. Hence the need for precision approach guidance, ILS or PAPI.
Touchdown scatter is (or should be) a by-product of a steep approach and the reduced threshold crossing height.
The original Dash 7 runway was ‘shortened’ (within the existing length) to limit operations to a level two airfield (jet) which had obstacle clearance and runway width / safety zone advantages.
The original ‘fixed distance markings’ were used to mark the optimum (last point of touchdown) zone. The teaching on the 146 was as remoak # 123 indicates. However, after a landing incident, it was recommended that additional lighting at the side of the runway be installed so that the crew could better define the point, as a long touchdown reduces the safety margin. IIRC a touchdown at the lights would assure a stop even with a spoiler failure (40%), but the crew had to recognise this and use full brake.
Since then the runway has been extended (level two torn up?) and the purpose of the touch down lights been reconsidered (146 interpretation still applies) as of a wide range of aircraft types now uses the airport.
In consultation with the local authority and residents, the 146 operation should have been limited to 6 deg for noise and obstacle clearance reasons.
5.5 evolved as a better choice for aircraft handling. The obstacle problems on 10 were solved with a ‘cat2’ quality glide slope – enables reduce obstacle clearances, and there was some 'help' with building regulations. Hence the need for precision approach guidance, ILS or PAPI.
Touchdown scatter is (or should be) a by-product of a steep approach and the reduced threshold crossing height.
The original Dash 7 runway was ‘shortened’ (within the existing length) to limit operations to a level two airfield (jet) which had obstacle clearance and runway width / safety zone advantages.
The original ‘fixed distance markings’ were used to mark the optimum (last point of touchdown) zone. The teaching on the 146 was as remoak # 123 indicates. However, after a landing incident, it was recommended that additional lighting at the side of the runway be installed so that the crew could better define the point, as a long touchdown reduces the safety margin. IIRC a touchdown at the lights would assure a stop even with a spoiler failure (40%), but the crew had to recognise this and use full brake.
Since then the runway has been extended (level two torn up?) and the purpose of the touch down lights been reconsidered (146 interpretation still applies) as of a wide range of aircraft types now uses the airport.
