Go Back  PPRuNe Forums > PPRuNe Worldwide > The Pacific: General Aviation & Questions
Reload this Page >

Question about 74 feet MEHT PAPI systems v 53 feet MEHT PAPI.

The Pacific: General Aviation & Questions The place for students, instructors and charter guys in Oz, NZ and the rest of Oceania.

Question about 74 feet MEHT PAPI systems v 53 feet MEHT PAPI.

Old 11th Jul 2015, 04:07
  #1 (permalink)  
Thread Starter
 
Join Date: Aug 2011
Location: Australia
Posts: 423
Likes: 0
Received 0 Likes on 0 Posts
Question about 74 feet MEHT PAPI systems v 53 feet MEHT PAPI.

Question:
In some Australian Jepps aerodrome charts, the PAPI published MEHT (Mean Eye Height at Threshold) can be as high as 74 feet. Melbourne is an example.
Launceston aerodrome chart shows MEHT as 53 feet. The 74 feet MEHT is for wide body types to account for the longer wheel base.

Does that mean with a 74 feet MEHT PAPI, the physical siting (position on the ground) of the four PAPI lights are further away from the landing threshold than a PAPI with 53 feet MEHT?
sheppey is offline  
Old 11th Jul 2015, 04:49
  #2 (permalink)  
 
Join Date: Apr 2008
Location: Australia
Posts: 15
Received 0 Likes on 0 Posts
As far as I'm aware, PAPI being a point source aid, the physical location of the lights is the same (ie circa 300m from the threshold) regardless of the MEHT. I presume the angle for 'on slope' would be adjusted for the MEHT required. Perhaps someone with greater knowledge could give a better answer?
Dukeunlimited is offline  
Old 11th Jul 2015, 05:01
  #3 (permalink)  
 
Join Date: Jun 2005
Location: in a box
Posts: 101
Likes: 0
Received 0 Likes on 0 Posts
My understanding Sheppey is that you are correct. If the PAPI remained the same distance from the threshold then you would have to come in on a higher angle to cross the threshold that 20ft higher. I doubt they would change the approach path angles for that 20ft difference rather than moving the PAPI further from the threshold. I'll have to compare next time I go into the 2 different types.
Hailstop3 is offline  
Old 11th Jul 2015, 05:16
  #4 (permalink)  
 
Join Date: Mar 2002
Location: Seat 1A
Posts: 8,532
Received 72 Likes on 41 Posts
Does that mean with a 74 feet MEHT PAPI, the physical siting (position on the ground) of the four PAPI lights are further away from the landing threshold than a PAPI with 53 feet MEHT?
Yes.......assuming same angle.
Capn Bloggs is offline  
Old 11th Jul 2015, 06:16
  #5 (permalink)  
 
Join Date: Jan 2008
Location: Australia
Posts: 265
Received 8 Likes on 5 Posts
I'll have to compare next time I go into the 2 different types.
You might notice the ground-car guys (or guys and gals, at a PC airport) rushing out to move the PAPI forward and backwards for the next approach ... it's impressive how quickly they can change things when aircraft are line-up on the ILS. Of course, in low-vis conditions, you probably won't see the car.

Seriously though - seeing as the PAPI at ML (as an example) is the standard 3 degrees, the difference must be due to the PAPI being located a little further down the runway - seeing as it is a longer runway, the touchdown zone (with markings and PAPI) is further from the threshold.
drpixie is offline  
Old 11th Jul 2015, 07:18
  #6 (permalink)  
 
Join Date: Apr 2008
Location: Australia
Posts: 15
Received 0 Likes on 0 Posts
As it turns out, adjusting the distance of the installation from the threshold (rather than an adjustment to the approach angle, which was larger than I had considered), to achieve the required MEHT for the runway (presumably for the largest type likely to use it) is quite right. I found the following link, which includes the formula for MEHT v Distance from threshold too, for those interested. I've learnt something new.

https://www.tc.gc.ca/eng/civilaviati...2-009-1202.htm
Dukeunlimited is offline  
Old 11th Jul 2015, 11:34
  #7 (permalink)  
 
Join Date: Jun 2006
Location: Brisbane
Posts: 265
Likes: 0
Received 0 Likes on 0 Posts
It isn't to do with the length of the runway, it's to do with the size of the aircraft it's designed for.

For example, MEL RWY27 is relatively short, but still has a 74' PAPI.

Large aircraft (most wide bodies) generally aim at the 1500' (450m) markers to achieve the desired wheel height over the threshold (e.g. 35'). That is where a 74' PAPI is located.

A 53' PAPI is located at the 1000' (300m) markers, and is designed for smaller aircraft (up to narrow body jets e.g. B737/A320).
Derfred is offline  
Old 11th Jul 2015, 13:04
  #8 (permalink)  
Thread Starter
 
Join Date: Aug 2011
Location: Australia
Posts: 423
Likes: 0
Received 0 Likes on 0 Posts
Dukeunlimited. Thank you very much for going to the trouble of sending the Canadian link to PAPI angles and installations. It was just what I was after.
To other contributors, thank you also for your comments.
sheppey is offline  
Old 11th Jul 2015, 23:32
  #9 (permalink)  
 
Join Date: Apr 2002
Location: Australia
Posts: 268
Likes: 0
Received 13 Likes on 2 Posts
Can anyone shed some light on the PAPI eye heights at Adelaide? It might have been a mistake when the original VASIs were installed but the opportunity to standardise the MEHT at Adelaide has been passed up many times.
Kelly Slater is offline  
Old 12th Jul 2015, 04:36
  #10 (permalink)  
 
Join Date: Apr 2008
Location: Australia
Posts: 15
Received 0 Likes on 0 Posts
No worries sheppey! As I mentioned, it was enlightening for me too.
Dukeunlimited is offline  
Old 29th Jul 2015, 01:10
  #11 (permalink)  
 
Join Date: Jul 2007
Location: Perth
Age: 55
Posts: 34
Received 2 Likes on 1 Post
When Orange extended it's runway to allow for the F100 over the Saab, we moved the PAPIs about 20m. "The standard wheel clearance over the threshold for the most demanding amongst the aircraft regularly using the runway"
I wish is offline  
Old 29th Jul 2015, 02:40
  #12 (permalink)  
 
Join Date: Jun 2000
Location: Australia
Posts: 4,186
Likes: 0
Received 6 Likes on 4 Posts
When Orange extended it's runway to allow for the F100 over the Saab, we moved the PAPIs about 20m. "The standard wheel clearance over the threshold for the most demanding amongst the aircraft regularly using the runway"
RAAF Base Williamtown has long been the home of fighter squadrons of the RAAF and is used by civilian aircraft. The current Air Services aerodrome chart reveals runways 12/30 have a PAPI set for a three degree slope with threshold crossing height of 50 feet.

From observation the crossing height of most jet fighters operating from Williamtown seems to be about 10 feet with aiming point to touch down very close to the runway threshold markers. Assuming therefore that "the standard wheel clearance over the threshold for the most demanding amongst the aircraft regularly using the runway and fighters use the Williamtown runways a lot more than civil arrivals, how come the PAPI is not set at ten feet over the threshold rather than 50 feet?
Centaurus is offline  
Old 29th Jul 2015, 16:38
  #13 (permalink)  
 
Join Date: Feb 2004
Location: Sydney
Posts: 39
Likes: 0
Received 0 Likes on 0 Posts
http://naca.central.cranfield.ac.uk/...rc/rm/3602.pdf
https://www.tc.gc.ca/media/documents...AC_302-009.pdf
http://code7700.com/pdfs/icao_annex_14_vol_1.pdf

Last edited by ventus45; 29th Jul 2015 at 16:49.
ventus45 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

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.