Glide slope vs Glidepath (EASA)

[overeasy]

Hi,

is anyone aware of a difference in legal definition between glide slope and glidepath. Anecdotally glide slope is the approach aid and glide path is trajectory, but is this referenced anywhere?

Many thanks

[oggers]

is anyone aware of a difference in legal definition between glide slope and glidepath

Notwithstanding the previous posted image, FAA Pilot controller glossary says the following (also reproduced in Jep glossary):
GLIDEPATH−
(See GLIDESLOPE.)
GLIDEPATH [ICAO]− A descent profile determined
for vertical guidance during a final approach.
GLIDESLOPE− Provides vertical guidance for
aircraft during approach and landing.

I understand it to mean that glidepath is ICAO terminology whilst glideslope is FAA, but they are the same thing. PANSOPS Vol 1 refers only to glide path.

[compressor stall]

I’m guessing one is tangible (we’ll sort of) in that a slope is a beam

A glide path, however, in calculated with maths.

[BBK]

Overeasy

Interesting question I’d never considered. Maybe it’s just different terms for exactly the same thing like landing gear and undercarriage or afterburner and reheat?

Also, your post got me thinking why the word “glide” is used? The BA B777 that tried that at LHR was very lucky to make the airport!

[Sleepybhudda]

Glideslope is associated with ICAO precision approaches, so normal ILS but also MLS or PAR. Since the advent of RNP you now have another type of vertical guidance but it didn't meet the ICAO criteria of precision approach so the term glidepath was used instead. Glidepath should only be seen in the civilian world when associated with ICAO classically classified non precision approach systems but still 3D approaches. Such as LPV, LNAV/VNAV, RNP AR APHC and the avionic specific LP+V, LNAV+V.

[PEI_3721]

Slope is that required, normally ground referenced; e.g.ILS GP is three deg.

Path is that being flown (or required) by the aircraft; aircraft referenced; e.g. flightpath is 4 deg, descending.

But PAPI = path indicator, whereas previously VASI = slope indicator !!!

Why the 'legal' tag ? Actions may be legal, but not necessarily safe.

[Meester proach]

Glideslope is associated with ICAO precision approaches, so normal ILS but also MLS or PAR. Since the advent of RNP you now have another type of vertical guidance but it didn't meet the ICAO criteria of precision approach so the term glidepath was used instead. Glidepath should only be seen in the civilian world when associated with ICAO classically classified non precision approach systems but still 3D approaches. Such as LPV, LNAV/VNAV, RNP AR APHC and the avionic specific LP+V, LNAV+V.. You nailed it there

[capngrog]

Slope is that required, normally ground referenced; e.g.ILS GP is three deg.

Path is that being flown (or required) by the aircraft; aircraft referenced; e.g. flightpath is 4 deg, descending.

But PAPI = path indicator, whereas previously VASI = slope indicator !!!

Why the 'legal' tag ? Actions may be legal, but not necessarily safe.

This is the explanation that made sense to me, but I have not flown a precision approach in decades. My limited knowledge base was acquired "long ago and far away".

Cheers,
Grog

[Denti]

As Sleepybhudda mentions probably the difference between precision and non precision but yet still vertically defined path. Back when i was still on the 737 it showed G/P on the FMA in an IAN non-precision approach (FMC computed glidepath) and G/S for precision approaches (ILS/GLS). Dunno if EASA uses something similar, but it does make sense in a way. Sadly now on the bus we do not have something as easy to use as IAN, although i hear the newer ones do have it.

[Check Airman]

I’ve always treated glide path as an RNAV glideslope, in much the same way I treat final course as an RNAV localiser.

How does it go? They're the same thing. Just different. :)

[overeasy]

Hi All,

Thanks very much for responses. Reason I ask is that steep approach criteria specifies a glide slope of 4.5 deg or more. If manoeuvring in a visual circle to land requires a glide path on the final approach of more than 4.5 degrees path, does this necessitate a steep approach approval for the Operator, Aircraft and crew.

[FlyingStone]

If manoeuvring in a visual circle to land requires a glide path on the final approach of more than 4.5 degrees path, does this necessitate a steep approach approval for the Operator, Aircraft and crew.

Any example of such approach in the world? Haven't seen a circle to a more than 4deg PAPI.

[PEI_3721]

From dated memory, the steep approach criteria evolved in two areas; an approach to an airport, without landing from a steep approach procedure vs approaching a runway to land, maintaining the approach angle.

Examples were Lugano, where the approach was into a valley, aiming short of the runway which required the aircraft to transition to a lower - PAPI defined final approach to land (GA terrain issue).
These operations may not require special aircraft or crew approval, depending on the type of operation and regulator (country). Obviously the aircraft had to be capable of flying the initial approach 'path', but not necessarily landing from a steep 'angle'.

Alternatively London City involves landing directly from the steep approach and requires full approval, particularly that the aircraft could maintain the required glide path (ILS or PAPI) in all conditions and be flared from the steeper angle.

Thus if a circle-to-land procedure involves a landing flare directly from a steep final approach, then both crew and aircraft should be approved, but check type of operation and regulation, e.g. USA part 23 not required, part 25 would be; EASA, probably all commercial operations.
There could be wriggle-room for a visual only final approach and need to meet icing configuration / thrust requirements or not, but the flare could still be limiting.

World example - Aspen used to allow approach to circle, but then Nav aids change / improve.

[overeasy]

Hi,

Yes I think that is where it is at. The airport in question is Annecy LFLP. Interestingly there seems to be no requirement from the airport to be steep approach capable to use RWY 22 for landing and requires no special training if the WX is better than 3,000 and 5k. The PAPI glidepath set to 5.3 deg. Steep approach definition refers to a glideslope specifically not glide path hence my original question.

[D-OCHO]

But PAPI = path indicator, whereas previously VASI = slope indicator !!!
PAPI and VASI are 2 completely different systems.

[teamax]

CAP 413 only uses the term Glidepath, not glideslope.

[happybiker]

The UK ANO and most CAA publications refer to the term glideslope