Go Back  PPRuNe Forums > Flight Deck Forums > Tech Log
Reload this Page >

Glide slope vs Glidepath (EASA)

Tech Log The very best in practical technical discussion on the web

Glide slope vs Glidepath (EASA)

Old 11th Oct 2020, 09:22
  #1 (permalink)  
Thread Starter
 
Join Date: Aug 2002
Location: U.K
Posts: 26
Glide slope vs Glidepath (EASA)

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
overeasy is offline  
Old 11th Oct 2020, 09:38
  #2 (permalink)  
 
Join Date: May 2020
Location: somewhere beyond the forest
Posts: 27

usedtobeATC is offline  
Old 11th Oct 2020, 10:09
  #3 (permalink)  
 
Join Date: Nov 2005
Location: Zulu Time Zone
Posts: 706
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.
oggers is offline  
Old 11th Oct 2020, 10:33
  #4 (permalink)  
 
Join Date: Feb 2000
Location: 500 miles from Chaikhosi, Yogistan
Posts: 3,756
Im guessing one is tangible (well sort of) in that a slope is a beam

A glide path, however, in calculated with maths.
compressor stall is offline  
Old 11th Oct 2020, 12:05
  #5 (permalink)  
BBK
 
Join Date: Feb 2001
Location: UK
Posts: 418
Overeasy

Interesting question Id never considered. Maybe its 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!

BBK is offline  
Old 11th Oct 2020, 12:16
  #6 (permalink)  
 
Join Date: May 2007
Location: UK
Age: 37
Posts: 103
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.
Sleepybhudda is offline  
Old 11th Oct 2020, 12:47
  #7 (permalink)  
 
Join Date: Mar 2006
Location: England
Posts: 889
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.
PEI_3721 is offline  
Old 11th Oct 2020, 14:15
  #8 (permalink)  
 
Join Date: Dec 2014
Location: Uk
Posts: 120
Originally Posted by Sleepybhudda View Post
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
Meester proach is offline  
Old 11th Oct 2020, 14:54
  #9 (permalink)  
 
Join Date: Nov 2015
Location: Paisley, Florida USA
Posts: 250
Originally Posted by PEI_3721 View Post
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
capngrog is offline  
Old 11th Oct 2020, 18:47
  #10 (permalink)  
 
Join Date: Mar 2001
Location: I wouldn't know.
Posts: 4,131
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.
Denti is offline  
Old 11th Oct 2020, 19:51
  #11 (permalink)  
 
Join Date: May 2020
Location: somewhere beyond the forest
Posts: 27

usedtobeATC is offline  
Old 11th Oct 2020, 20:00
  #12 (permalink)  
 
Join Date: Mar 2006
Location: USA
Posts: 1,880
Ive 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.
Check Airman is online now  
Old 13th Oct 2020, 22:07
  #13 (permalink)  
Thread Starter
 
Join Date: Aug 2002
Location: U.K
Posts: 26
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.

overeasy is offline  
Old 13th Oct 2020, 22:57
  #14 (permalink)  
 
Join Date: Apr 2010
Location: IRS NAV ONLY
Posts: 948
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.
FlyingStone is offline  
Old 14th Oct 2020, 07:40
  #15 (permalink)  
 
Join Date: Mar 2006
Location: England
Posts: 889
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.
PEI_3721 is offline  
Old 15th Oct 2020, 15:37
  #16 (permalink)  
Thread Starter
 
Join Date: Aug 2002
Location: U.K
Posts: 26
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.
overeasy is offline  
Old 29th Oct 2020, 14:07
  #17 (permalink)  
 
Join Date: Jan 2003
Location: Europe, Africa
Posts: 78
Originally Posted by PEI_3721 View Post
But PAPI = path indicator, whereas previously VASI = slope indicator !!!
PAPI and VASI are 2 completely different systems.
D-OCHO is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.