ILS question
Thread Starter
Join Date: Sep 2005
Location: los angeles
Posts: 17
Likes: 0
Received 0 Likes
on
0 Posts
ILS question
If you are 15 miles out on glide slope with a 3 degree angle, how high are you agl? Does anyone have a good quick rule of thumb for this?
p.s while im here, if a brand new engine is at 1.8 epr and producing 60,600 lbs of thrust, ten years later will it still produce the same thrust for 1.8?
thanks in advance for any inputs,
D
p.s while im here, if a brand new engine is at 1.8 epr and producing 60,600 lbs of thrust, ten years later will it still produce the same thrust for 1.8?
thanks in advance for any inputs,
D
Gender Faculty Specialist
A good rule of thumb is 3 times your height.
Therefore at 15 miles on a 3 degree slope you should be at 5000feet.
Also a rule of thumb for working out what your vertical speed should be on a 3 degree slope is 5 times your groundspeed. ie. 150kts x 5 750 feet per minute.
Therefore at 15 miles on a 3 degree slope you should be at 5000feet.
Also a rule of thumb for working out what your vertical speed should be on a 3 degree slope is 5 times your groundspeed. ie. 150kts x 5 750 feet per minute.
3 x your distance is a bit closer I think (not to mention being easier to work out when you want to know how high you should be at a specific distance.) So at 15 miles you want to be 4,500'.
Guest
Posts: n/a
Another good way of working out your ROD is dividing your GS by 2 and adding a 0 at the end of your answer.
ie, GS of 160/2 = 80 + 0 = 800 feet a min,
GS of 150/2 = 75 + 0 = 750 feet a min,
GS of 140/2 = 70 + 0 = 700 feet a min
GS of 136/2 = 68 + 0 + 680 feet a min and so on.
Seems to work and gives the same answer as the GS x 5 rule. Depends on how good your mental arithmatic is I suppose.
ie, GS of 160/2 = 80 + 0 = 800 feet a min,
GS of 150/2 = 75 + 0 = 750 feet a min,
GS of 140/2 = 70 + 0 = 700 feet a min
GS of 136/2 = 68 + 0 + 680 feet a min and so on.
Seems to work and gives the same answer as the GS x 5 rule. Depends on how good your mental arithmatic is I suppose.
Join Date: Jul 2002
Location: California USA
Posts: 719
Likes: 0
Received 0 Likes
on
0 Posts
If you are 15 miles out on glide slope with a 3 degree angle, how high are you agl?
Just a paranoid ATC putting his two cents in...
Dave
Join Date: Jan 1999
Location: hongkong
Posts: 187
Likes: 0
Received 0 Likes
on
0 Posts
As to the EPR question...simple answer yes! The EGT will go higher as the engine gets older but the thrust will be exactly the same assuming of course that the EPR measuring systems are OK. This is one of the benefits of an EPR system as opposed to just measuring N1 I am told.
Join Date: Jan 2003
Location: Europe
Posts: 270
Likes: 0
Received 0 Likes
on
0 Posts
AerocatS2A answer is correct.
On a 3° GS you'll lose about 300' per NM. So when you are 15 NM out on GS you should be at 4500' above airport elevation (or rather threshold elevation).
Generally, to find the number of feet per NM descent, multiply the descent angle by 100. So with a 3° angle you will get 3x100 = 300'/NM. That leads us to 4500' at 15NM out on GS.
With a 2.5° angle: 2.5x100 = 250'/NM. At 15NM out on GS you should be at about 3750' above threshold elevation.
On a 3° GS you'll lose about 300' per NM. So when you are 15 NM out on GS you should be at 4500' above airport elevation (or rather threshold elevation).
Generally, to find the number of feet per NM descent, multiply the descent angle by 100. So with a 3° angle you will get 3x100 = 300'/NM. That leads us to 4500' at 15NM out on GS.
With a 2.5° angle: 2.5x100 = 250'/NM. At 15NM out on GS you should be at about 3750' above threshold elevation.
Join Date: Jul 2006
Location: Australia
Age: 35
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
Hi everyone, I was reading a book on IFR and ILS approaches and came across the term Lobes'. The book was a little vague on what a 'Lobe' does except to say it had somehting to do with the glidepath 
. If anyone could should some light on the matter it would be appreciated.
Newbie1
. If anyone could should some light on the matter it would be appreciated. Newbie1
Join Date: Jun 1999
Location: Hong Kong
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
ILS Lobes
Quick Google search "ILS systems lobes" yielded many results, this link goes to a technical document but show, digramatically the lobe concept.
http://www.pn.ewi.tudelft.nl/educati...2/notes/h7.pdf
http://www.pn.ewi.tudelft.nl/educati...2/notes/h7.pdf
Join Date: Apr 2006
Location: Gods Country
Posts: 87
Likes: 0
Received 0 Likes
on
0 Posts
Cross Checks.
A 3 degree glide slope gives a change of 320ft in height for every 1NM. Therefore at 10NM from the Rwy. Your altimeter should read 3200 ft AGL. If the elevation of the runway is 200 ft then the altimeter will read 3400ft, because the altimeter is reading height above Mean Sea Level.
Newbie1.
Lobes are those funny looking things that looks like a stretched bannana on any LLZ, GS diagram. If you can get hold of the Oxford Air Training Radio Aids book it explains all the aspects of the construction and use of the ILS.
Newbie1.
Lobes are those funny looking things that looks like a stretched bannana on any LLZ, GS diagram. If you can get hold of the Oxford Air Training Radio Aids book it explains all the aspects of the construction and use of the ILS.
Guest
Posts: n/a
Originally Posted by Fournicator
shgsaint:
By dividing by 2 then multiplying by 10 you are just multiplying by 5. You haven't discovered some amazing new aviation rule of thumb, just learnt an easier way to do maths that most of us figured out at primary school!
By dividing by 2 then multiplying by 10 you are just multiplying by 5. You haven't discovered some amazing new aviation rule of thumb, just learnt an easier way to do maths that most of us figured out at primary school!
I don't appreciate the last remark. KISS (Keep It Simple Stupid)
Join Date: Apr 2006
Location: Gods Country
Posts: 87
Likes: 0
Received 0 Likes
on
0 Posts
issi noho
Well obviously the altimeter reads above the datum set, but when one is flying an ILS the pressure altimeter is normally set to the aerodrome QNH unless one is flying in the military or as I read in Russia where they use QFE. Thats what I was getting at.
Guest
Posts: n/a
Originally Posted by Fournicator
Sorry if I hurt your feelings.
I'll be the first to admit my maths is a little rusty. But then not being a professional pilot it doesn't need to be sharp.
Just my preferred way of remembering/working out the ROD on an ILS.