Hi,

 

I live underneath the ILS approach path for Rwy's 18L, C, and R of EHAM with C coming right over my house. I bet that the DME of the aircraft reads something like 11 Nm when they pas over my house.

 

I noticed it many times before and today i thought enough is enough. I need to know !

 

What could be the reason that sometimes the approaching aircraft are flying much lower than usually when passing over my house ??...... I'd say the difference could easily be 500 feet possibly more....

 

It's not like the G/S beam can be adjusted by ATC just like that, can it ?? Why would EHAM ATC sometimes command all aircraft to approach these runways at a much lower altitude then normally is the case all of a sudden ??...

 

On these occasions it just feels like the airport has been moved to the north a couple of miles...

 

Would really appreciate it if someone could enlighten me about this, to me, remarkable mystery.

 

Thanks very much in advance !

 

Cheers,

Jan

Controllers tend to establish aircraft around about 10nm from the runway, generally. Some aircraft may have descended quickly to their assigned altitude, while others may still be descending, or others could have captured the glideslope already, and so each passing aircraft may be at a different altitude. If you lived closer to the airport, you would probably see far greater consistency in terms of the aircraft's altitudes on approach, as they are more likely to be established by that point.

I think the matter boils down to the placement of the two runways... 18R & 18C and which runway is in use at the time.

 

If you compare the two ILS's (18C & 18R) and trying to give a "geofix" using Google Earth...

• 18C: The FAF is 3000'MSL at 9.3DME ZWA (ZWA is ILS for 18C). 11.3DME ZWA appears to be near "Krommeniedijk" on Google (a city?). Down to 2000'MSL by 6.2DME ZWA which seems to correspond to Nauerna.
  
• 18R: Aircraft should be at 3000'MSL by 10.8DME VPB (VPB is ILS for 18R). 10.8DME VPB appears to be near "Gr Dorregeest". Down to 2000'MSL by 6.2DME VPB (the FAF) which seems to be roughly a mile southwest of "Assendelft".
  

Note that the approach end of Rwy 18C is near the depature end of Rwy 18R... and Rwy 18R is nearly 2nm long ("it just feels like the airport has been moved to the north a couple of miles").

 

Apologies on names (if misspellings... using the U.S. version of Google Earth).

 

-Rob

Since the typical accepted practice for capturing an ILS glideslope signal is to fly into the signal beam from underneath it rather than from above it (this is to avoid accidentally locking onto a false ground-reflected glideslope signal that is higher up, which is rare but it can happen), this means that providing the aircraft is not below its minimum cleared initial approach altitude before being fully established on the ILS (both localiser and glideslope) there could easily be a few hundred feet difference between one flight and the next as they fly into the glideslope signal.

 

You see that kind of thing quite a bit at many airports, although as Rob points out, it may also be that aircraft you see are in fact going for one of a couple of parallel runways with different threshholds, since when still over ten miles out, they may not be in perfect alignment laterally with either runway, especially if there is a crosswind component. Technically and legally, there could be as much as 2,000 feet lateral difference (.3 of a nautical mile) and it would still be within the required parameters for an initial approach, although that much of a discrepancy is rather unlikely.

 

Thus it would be difficult to know for sure which runway they were heading for from 11 miles DME without monitoring ATC. Which is I suppose something you could try, in order to determine more about the matter if you were really curious, although (cue disclaimer) in many countries it is actually illegal to monitor ATC transmissions without a good reason, not that it is likely the police would come after you for doing so, since many plane spotters do so right outside the airport and never get hassled, but it is as well to be aware of that being the case.

 

Al

At Heathrow (EGLL) the Noise Abatement Procedures prohibit flying below the glidepath below 2500 ft (27R&L) or 3000ft (09R&L).

 

a. Between 0600 and 2330 hours (local time) where the aircraft is approaching runway 27 (L or R) and is using the ILS in IMC or VMC it shall not descend on the glidepath below an altitude of 2500 ft (Heathrow QNH) before being established on the localizer, nor thereafter fly below the glidepath. An aircraft approaching without assistance from the ILS shall follow a descent path which will not result in its being at any time lower than the approach path that would be followed by an aircraft using the ILS glidepath, and shall follow a track to intercept the extended runway centre-line at or above 2500 ft...

I live underneath the ILS approach path for Rwy's 18L, C, and R of EHAM with C coming right over my house. I bet that the DME of the aircraft reads something like 11 Nm when they pas over my house.

 

I noticed it many times before and today i thought enough is enough. I need to know !

 

Sometimes it can be down to the skills (or lack of) of the pilot. Some years ago Pakistan Airlines were often fined for noise abatement violations for approaching too low inbound to Manchester.

 

As you live close to Schiphol you might find this website useful in identifying the culprits. http://www.flightradar24.com

 

It's pretty much real-time updating. I can track inbounds to Manchester and as they pass over the A34 road I can look out of my patio window and see them. The height and speed are shown for any selected aircraft. It's a brilliant service.

 

As I type this I see there's an inbound Transavia 737-800 which looks like he might be about to fly over your house!

Thanks for the reply, gents, appreciate it !

 

The thing is that i can see ALL aircraft at a much lower altitude than normally is the case. No matter if their assigned runway is 18C or 18R ( i can see them both, the 18C path is above my house (Krommenie), 18R a mile or two to the west (Uitgeest). During rush hours they'll come in one after the other with just a couple minutes in between, both for 18C and 18R together ( 18L is seldom used for landing ).

 

Thanks for the'geofix', Rob. Krommeniedijk is an 'offshoot' of my little Krommenie village. Nice to see i got 11 DME just about right. Naurena, Dorregeest (Uitgeest), Assendelft all correct, yes.

 

@ Al, you bet i've got a scanner dedicated to Schiphol ATC but haven't used it for some time. I was very exited about it in the beginning but got bored with it after a while. It's always the same, each and every day. ( and a good thing too, naturally.. ).

 

I experienced only two really exiting occasions : one was the 'official declaration' of a UFO by an airliner crew in the middle of the night, and the other concerned a GA aircraft ( now banned from Schiphol ) that made a 'normal' landing while the pilot was ordered to execute a 'displaced threshold' landing. The controller was not amused to say the least and ordered the pilot to leave his aircraft immidiately after parking and report to the airport authorities bureau instantly. :Nail Biting:

 

I might go look for the thing (a Bearcat so and so) and hook it up again and see if it still works.

 

Anyway, i've been looking at airliners passing over my house on their way to 18C and 18R ( formerly only 19R...) for years and years so i think i can say i'm an 'expert' when it comes that. Always wished they'd be a little lower. Now, for some time already, my wish seems to have come true, atleast for a couple times per month. Because ALL aircraft fly at this significant lower altitude one would tend to think that the G/S path has been adjusted. I know full well that such would be highly unlikely hence my question.

 

I usually walk my dog for an hour or so during morning rushhour at Schiphol,and when 18C and 18R are active nothing beats the sight of a 747 making its turn to capture the localizer with the morning sun gleaming all over it against the beautiful dutch summer sky. Especially at this remarkable lower altitude ! B)

 

Ray, thanks for the link ! Didn't know about that. Holy Moly! Amazing !!!

 

cheers,

jan