Visual Approach Path Indicators (VASI / PAPI / AAI)

**Carnaby** · 27-01-2012, 10:08

Here is a repeat of the post mentioned earlier

Drem Mk.1 in 1941 had 230V, 250W Angle of Glide Indicators - one only on the left of each runway, showing red / green / amber on approach. It was optimised on 5 degrees.

Later that year, with the advent of Drem Mk.2, a slow rotating shutter was added to make them flicker. They were renamed AAIs and a second was now added on the right of the runway. Later still the left unit was lowered by 0.5 degree, and the RH one was raised by the same amount.

This resulted in green and red when slightly too low, green and green when correct, and amber and green when slightly too high. Clearly two reds or two ambers meant way out!

**AiXAdmin** · 27-01-2012, 10:38

It was optimised on 5 degrees.

That answers the question I nearly posed yesterday... OK for the aircraft of the day, but would be a couple of degrees too steep with the advent of jets. (Same for any associated airfield approach aids such as ILS/PAR I guess)

**mawganmad** · 27-01-2012, 19:20

Bit steeper than the 3 degrees for VASIs/PAPIs.

**Dr_Bishop** · 30-01-2012, 10:11

The majority of VASI and PAPI were set to 3 degrees.

Places like Binbrook were set to 2.5 degrees.

IIRC, London City Airport are set at 7 degrees!

**RAFerk** · 05-03-2012, 22:56

sighting1.jpg sighting2.jpg sighting3.jpg sighting4.jpg sighting5.jpg

I have attached photos of a sighting device that I bought with some other RAF items. This has something to do with setting up landing lights or similar. Can anyone shed more light on the item and maybe say how it was used. I would like to know for when I am asked what it is and how it works. I do know an ex RAF chap who`s job it was, (amongst others), to check approach lights and he used something similar which he had to attach to a platform at the end of the runway. This was in the early 1950s.

**canberra** · 06-03-2012, 17:36

On 27 at Leuchars it was a 2.5 degree glidepath. O9 and 22 it was 3 degrees, and on 09 it was 3 degrees because of the road, 22 was because of D604 aka Barry Buddon.

**Dr_Bishop** · 06-03-2012, 19:39

Originally Posted by canberra

On 27 at Leuchars it was a 2.5 degree glidepath. O9 and 22 it was 3 degrees, and on 09 it was 3 degrees because of the road, 22 was because of D604 aka Barry Buddon.

Well done Canberra. You have just past your TT for 2012!

**canberra** · 06-03-2012, 22:36

Im surprised you have marked me down for not knowing what it was on 04!! But in all my time at Leuchars I never saw anyone land on 04, and I only saw four Tornados take off on it.

**Dr_Bishop** · 07-03-2012, 08:00

Originally Posted by canberra

Im surprised you have marked me down for not knowing what it was on 04!! But in all my time at Leuchars I never saw anyone land on 04, and I only saw four Tornados take off on it.

04....?

I never saw anything take off or land on it in two years.

**Carnaby** · 19-03-2012, 22:07

Originally Posted by RAFerk

sighting1.jpg sighting2.jpg sighting3.jpg sighting4.jpg sighting5.jpg

I have attached photos of a sighting device that I bought with some other RAF items. This has something to do with setting up landing lights or similar. Can anyone shed more light on the item and maybe say how it was used. I would like to know for when I am asked what it is and how it works. I do know an ex RAF chap who`s job it was, (amongst others), to check approach lights and he used something similar which he had to attach to a platform at the end of the runway. This was in the early 1950s.

It is for adjusting the High Intensity GEC LA/11 Approach Light which looks like Post #343, presumably to 3 degrees. These lamps are more commonly seen as elevated runway fittings. I guess the angle of the latter would be lower as might the beam width / height.