Runways, Aprons and Taxiways

Yorkieflyer said:

It’s not the Glideslope structure , that’s the vertical red and white structure at the SIDE of the runway. The glideslope structure is abeam the touchdown point on the runway and has no bearing on TAKE OFF Distance Available (TODA).

What has been mentioned is the localiser structure. This is the orange Structure at the ENDS of the runway. The localiser antenna for runway 32 is at the chevon end, it radiates an extended centreline alone the runway and along the approach line, of course that means runway 14’s localiser antenna is at the far end of 14, ie the Horsforth end.
These antennas are a fence like structure and stand above runway level. This means for an aircraft taking off from runway 32 for example must pass over the 32 antenna (at the far (chevin) end) a minimum of 35 ft above it. To achieve this it would need to be wheels off by a certain point on the runway. If as has been suggested this can be lowered, it would mean you could be wheels off slightly further along the runway to achieve the 35’ over the now lower structure. Thereby increasing the TODA (Take Off Distance Available)

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Thanks for the explanation of what each structure is on the air field, myself and i think others were abit confused by it all! I bet reducing the height of the antennas will only give about 50 metres or so extra take off distance, also does anyone know at what point at each end of the runway an aircraft must be off the ground as over the years I've seen many lift off very late with only few hundred metres left?

KARFA
My apologies, TORA should have read TODA (Take off run available + Clearway)
However the definition and requirements remain the same. Although you may feel uncomfortable with the possibility of a minimum vertical distance of only 35 feet that is in fact the legal requirement as set out by ICAO.
The ASDA or accelerate stop distance is something different however a pilot’s take off performance calculation is figure based upon all of these distances, requirements, weights, environmental conditions etc. and the most restrictive is the limiting.

This will result in more than just a longer runway

There is some extra technical "bumph" that is being overlooked here. Beyond just gaining a bit of extra takeoff distance (of course every little helps), the airport will get a massive boost to its CAT III reliability and freeing up space on the apron. This is big news IMHO and something that was missed at the meeting!

Here is the breakdown of those hidden wins

Currently, the old ILS system has a very wide "safety bubble" (the Sensitive Area). Because the signal is so finicky, Stands 1-5 (the ones closest to the terminal) are often "restricted" which is probably why the airport previously thought nothing of building portacabins on them.

The problem at the moment is, if a plane is parked on one of these stands or pushing back, its big metal tail can interfere with the landing signal. This often means these stands have to stay empty or operations have to be paused during heavy fog.

The new, "tighter" localiser beam won't be as affected by planes parked at the terminal. This "unlocks" those stands for full-time use, even in the middle of a traditional Leeds pea-souper!

In the past, when the fog rolled in, ATC had to keep everyone miles back at distant holding points to keep the signal clear. The modern equipment allows for much more relaxed "Low Visibility Procedures."

Aircraft can wait much closer to the runway without "breaking" the landing beam for the next arrival. This means fewer gaps in the schedule and a much more reliable "conveyor belt" of flights during the morning rush.

By modernising the localisers, LBA isn't just making the runway longer, they are making it smarter. They'll be a move away from a "fragile" signal that forces everyone to keep their distance, to a robust "laser-like" signal that allows the airport to function almost normally, even when the weather is doing its worst.

Sounds like a no-brainier, but also begs the question why it hasn’t been done sooner? I would have thought the cost would be reasonable and would be offset by the reduction in diversions and knock on revenue the airport would raise/keep.

Yorkieflyer said:

However the definition and requirements remain the same. Although you may feel uncomfortable with the possibility of a minimum vertical distance of only 35 feet that is in fact the legal requirement as set out by ICAO.
The ASDA or accelerate stop distance is something different however a pilot’s take off performance calculation is figure based upon all of these distances, requirements, weights, environmental conditions etc. and the most restrictive is the limiting.

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i don't feel uncomfortable with it, i am suggesting in normal operations you would not be anywhere near 35 feet vertical from a localiser at the other end of the runway when taking off- you would be significantly higher by that point!

how late do you think aircraft rotate on a runway and how slowly do you think they climb?

Well, having flown them for 34 years I’ve a reasonable idea, thanks.

KARFA said:

i don't feel uncomfortable with it, i am suggesting in normal operations you would not be anywhere near 35 feet vertical from a localiser at the other end of the runway when taking off- you would be significantly higher by that point!

how late do you think aircraft rotate on a runway and how slowly do you think they climb?

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The point is the extra distance can be calculated into the available take-off distance even if you have no intention of using it.

Finger66 said:

Fewer stands and bigger aircraft. Also fits a current narrative coming out of LBA

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Bare in mind more stands in front of the terminal will become available too.

KARFA said:

i don't feel uncomfortable with it, i am suggesting in normal operations you would not be anywhere near 35 feet vertical from a localiser at the other end of the runway when taking off- you would be significantly higher by that point!

how late do you think aircraft rotate on a runway and how slowly do you think they climb?

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Also bear in mind that each takeoff is calculated based on an engine failure at V1. On a relatively short runway such as LBA, takeoffs are generally field length limited rather than climb gradient limited (although with the Chevin, it's possible to be climb limited off RW32). If climb gradient is not a factor, the V1 speed can sometimes be lowered, allowing for a greater takeoff weight. But in this case, if the engine failed at V1, the aircraft would take longer to accelerate down the runway to rotate speed and also climb at a lower gradient due to the increased weight.

So what's being discussed does seem plausible, but I doubt it would have a meaningful impact in most cases. It might just be the difference maker though.

thanks. my suspicion is that the changes and benefits are really driven by replacing the localisers with one having higher number of antenna (i don't know how many the current ones have off the top of my head) - hence all the stuff about more robust ILS.

the new localisers would be lower anyway, so this potential minor benefit in takeoff distances is more of a by-product rather than something they are trying to do. as you say, it's unlikely to make much real difference to route/type viability.

LeedsPilot said:

Also bear in mind that each takeoff is calculated based on an engine failure at V1. On a relatively short runway such as LBA, takeoffs are generally field length limited rather than climb gradient limited (although with the Chevin, it's possible to be climb limited off RW32). If climb gradient is not a factor, the V1 speed can sometimes be lowered, allowing for a greater takeoff weight. But in this case, if the engine failed at V1, the aircraft would take longer to accelerate down the runway to rotate speed and also climb at a lower gradient due to the increased weight.

So what's being discussed does seem plausible, but I doubt it would have a meaningful impact in most cases. It might just be the difference maker though.

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I suppose the real benefit will come from the reduced interference on the ground. The airport has already said it is going to invest in ground radar so this would be the logical next step to improve low viz ops.