3.5 degree approach
Thread Starter
Join Date: May 2002
Location: Australia
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
3.5 degree approach
Does anyone out there know a quick rule of thumb for formulating rate of descent and altitude per NM for flying approaches other than 3 degrees.
Like the old 320ft per nm and half GS +50ft for ROD.
For example a NPA with a 3.5 degree profile.
THANKS
Like the old 320ft per nm and half GS +50ft for ROD.
For example a NPA with a 3.5 degree profile.
THANKS
No I dont know any rules of thumb. But going off 320'/nm that means 1 degree equals 106.666'. At YSCB the Rwy 30 PAPI angle is 3.9 degrees 416'/nm. So with some forward planning I would have some target altitudes for Rwy30 like 4000 at 5 track miles etc.
On a more serious note I would fly an NPA using the published distance/altitude scale. A few reasons are, the guy beside you will know 'whats going on'(unless briefed). When things turn sour its so much easier flying something that is familiar(standard) and published in front of you. Even when you fly an NPA such as Rwy 30 at YSCB I would use the 3 degree dist/alt scale until visual and then fly level or reduce my rate of descent to intercept a visual descent point for 3.9 degrees with the aid of the PAPI.
As far as calculting a Rate of Descent try your 'whizz wheel'.
For 3.9 degrees we already know 416'/nm or 2.4nm/1000'. Put the time index on your GS and check your inner scale at 416 and there you have it, a number to put into the VS.
example:300 GS, 416 inner scale = 2400 FPM RoD.
For your example(3.5 degrees) 320'+53'=373'/nm
150 GS, 373 inner scale = 935 FPM RoD
Where is the 3.5 degree NPA?
Safe flying, hoss
On a more serious note I would fly an NPA using the published distance/altitude scale. A few reasons are, the guy beside you will know 'whats going on'(unless briefed). When things turn sour its so much easier flying something that is familiar(standard) and published in front of you. Even when you fly an NPA such as Rwy 30 at YSCB I would use the 3 degree dist/alt scale until visual and then fly level or reduce my rate of descent to intercept a visual descent point for 3.9 degrees with the aid of the PAPI.
As far as calculting a Rate of Descent try your 'whizz wheel'.
For 3.9 degrees we already know 416'/nm or 2.4nm/1000'. Put the time index on your GS and check your inner scale at 416 and there you have it, a number to put into the VS.
example:300 GS, 416 inner scale = 2400 FPM RoD.
For your example(3.5 degrees) 320'+53'=373'/nm
150 GS, 373 inner scale = 935 FPM RoD
Where is the 3.5 degree NPA?
Safe flying, hoss
Last edited by hoss; 18th Mar 2003 at 00:21.
I went berserk with the high school trigonometry and came up with this for feet per nm - it's easy and works pretty well, but over-estimates by somewhere between 10 and 20 feet per nm depending what angle you're using - rough enough for me, anyway.
Rule of thumb: Feet per nautical mile = Degree of glidepath x 100, plus 10 %.
eg for 3.5 degrees, = 350 + 35 = 385
(real answer should be 372 using Tan etc.)
To get fpm, I would then multiply by groundspeed in nm / min.
eg for 110 kt finals g/s, which is 1.8333 (etc) nm / min, the accurate answer would be 1.8333 x 372 = 706 fpm, done on calculator or whizz wheel.
To do it in my head, I'd get the first answer for ft / nm (385), then say, 110 kt is about 120 kt (2 nm/min) minus 10%. So the rate of descent should be (2 x 385) - 10%, = 770 -77 = 693 ft / min.
Again that comes out within 20 fpm or so, so I wouldn't complicate it any further.
To check with another example, say 4.5 degree slope and 140 kt final:
ft per nm should be 450 + 45, = 495 (correct answer 479).
140 kt is close enough to 2 nm per min + 20%, so ROD should be (2 x 495) + 20%, = 990 + 200 = 1190 fpm.
Correct answer should have been 1118 fpm, about 80 fpm out, but OK to use I think.
Rule of thumb: Feet per nautical mile = Degree of glidepath x 100, plus 10 %.
eg for 3.5 degrees, = 350 + 35 = 385
(real answer should be 372 using Tan etc.)
To get fpm, I would then multiply by groundspeed in nm / min.
eg for 110 kt finals g/s, which is 1.8333 (etc) nm / min, the accurate answer would be 1.8333 x 372 = 706 fpm, done on calculator or whizz wheel.
To do it in my head, I'd get the first answer for ft / nm (385), then say, 110 kt is about 120 kt (2 nm/min) minus 10%. So the rate of descent should be (2 x 385) - 10%, = 770 -77 = 693 ft / min.
Again that comes out within 20 fpm or so, so I wouldn't complicate it any further.
To check with another example, say 4.5 degree slope and 140 kt final:
ft per nm should be 450 + 45, = 495 (correct answer 479).
140 kt is close enough to 2 nm per min + 20%, so ROD should be (2 x 495) + 20%, = 990 + 200 = 1190 fpm.
Correct answer should have been 1118 fpm, about 80 fpm out, but OK to use I think.
Thread Starter
Join Date: May 2002
Location: Australia
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
Thanks guys! I recently did a cyclic (sim) at KLAX with an approach to RWY25 VOR/DME. From the FAF the profile is 3.49 degrees. The plate gives the required ROD for different ground speeds, but no ALT/NM check information. It turned out to be no drama anyway with the dynamic arc, I just like to back up (mentally) what I'm seeing.
Thanks again.
Thought I would try 1 more question as it's been bugging me for ages:
With an aid running on standby power I've been told it will transmit an extra . on the morse ident, I'd imagine this would stump most pilots and would like some clarification or a reference (looked everywhere I can think of).
I'd say I've asked close to 50 captains, with no info yet.
Thought I would try 1 more question as it's been bugging me for ages:
With an aid running on standby power I've been told it will transmit an extra . on the morse ident, I'd imagine this would stump most pilots and would like some clarification or a reference (looked everywhere I can think of).
I'd say I've asked close to 50 captains, with no info yet.
Thanks again.
Thought I would try 1 more question as it's been bugging me for ages:
With an aid running on standby power I've been told it will transmit an extra . on the morse ident, I'd imagine this would stump most pilots and would like some clarification or a reference (looked everywhere I can think of).
I'd say I've asked close to 50 captains, with no info yet.
Thought I would try 1 more question as it's been bugging me for ages:
With an aid running on standby power I've been told it will transmit an extra . on the morse ident, I'd imagine this would stump most pilots and would like some clarification or a reference (looked everywhere I can think of).
I'd say I've asked close to 50 captains, with no info yet.
Heres what I found
.
NDB reliability. The majority of NDB ground stations actually consist of two separate transmitters, a primary and a standby unit. Certain transmission parameters are constantly monitored and, if any of these strays outside allowable limits, the primary unit is switched off and the standby transmitter automatically activated. In this event the standby transmitter adds a dot after the identification ( E ). Such beacons are Pilot-monitored and the appropriate ATS unit should be informed if the equipment is operating on the standby source. Should the standby unit subsequently develop a fault, then it too will be deactivated, rendering the NDB unserviceable. Note the Pilot using theaffected station has no warning or control over this process.
My guess is E could stand for emergency or enroute or emission or erronious or equipment etc.
Hey its a Rumour network after all. Does this mean I can be a Captain now?
Safe flying, hoss
.NDB reliability. The majority of NDB ground stations actually consist of two separate transmitters, a primary and a standby unit. Certain transmission parameters are constantly monitored and, if any of these strays outside allowable limits, the primary unit is switched off and the standby transmitter automatically activated. In this event the standby transmitter adds a dot after the identification ( E ). Such beacons are Pilot-monitored and the appropriate ATS unit should be informed if the equipment is operating on the standby source. Should the standby unit subsequently develop a fault, then it too will be deactivated, rendering the NDB unserviceable. Note the Pilot using theaffected station has no warning or control over this process.
My guess is E could stand for emergency or enroute or emission or erronious or equipment etc.
Hey its a Rumour network after all. Does this mean I can be a Captain now?
Safe flying, hoss
Last edited by hoss; 18th Mar 2003 at 03:35.
PPRuNeaholic
Join Date: Jun 2000
Location: Cairns FNQ
Posts: 3,255
Likes: 0
Received 0 Likes
on
0 Posts
That's the sort of thing I'd expect a captain to know - and even an effoh for that matter. With so many captains who don't know about it, Fat Ass, it seems like the T+C guys don't know it either. Perhaps you can do the company a favour and bring it up, tactfully of course with the T+C troops... before some smart ass FOI catches them all out and embarrasses the hell out of the company.
with the T+C troops... before some smart ass FOI catches them all out and embarrasses the hell out of the company.
On Airbus we use .6 times the gradient stated on the appoach chart minus .2 for non-precision approach. This will give you a flight path angle which is easily converted to ft per nm.
For example, approach gradient specified on Jep chart is 5%.
FPA= 5times decimal 6 minus decimal2=2.8 degrees.
2.8 degrees equals 280 ft per nm.
For example, approach gradient specified on Jep chart is 5%.
FPA= 5times decimal 6 minus decimal2=2.8 degrees.
2.8 degrees equals 280 ft per nm.
Fat Ass,
You never flew with Bill H, did you. Had you endured a long trip with him, you would have had that info plus heaps more jammed into your ears at often inopportune times. He's sadly missed since his retirement - NOT.
BTW, Kolkata VOR (CEA) has been operating in that mode for years!!
You never flew with Bill H, did you. Had you endured a long trip with him, you would have had that info plus heaps more jammed into your ears at often inopportune times. He's sadly missed since his retirement - NOT.
BTW, Kolkata VOR (CEA) has been operating in that mode for years!!
Join Date: Jun 2000
Location: Bobawaba,Queensland,Australia
Posts: 22
Likes: 0
Received 0 Likes
on
0 Posts
To calculate ROD for various GS (200 knots or less)/glideslope, I use the following
for 3 degree slope GS x 5 plus 50' = ROD (140 kts x 5 + 50' = 750')
for 3.5 degrees GS x 6
for 4 degrees GS x 7
An alternative method is to use the wind side of the old whizz wheel. I use a Jepp CR 5. Set the TAS index against your GS (140 kts): against the required GS e.g. 3 degrees, read ROD of 732', 3.5 degrees 860' (close enough) and 4 degrees 975'.
for 3 degree slope GS x 5 plus 50' = ROD (140 kts x 5 + 50' = 750')
for 3.5 degrees GS x 6
for 4 degrees GS x 7
An alternative method is to use the wind side of the old whizz wheel. I use a Jepp CR 5. Set the TAS index against your GS (140 kts): against the required GS e.g. 3 degrees, read ROD of 732', 3.5 degrees 860' (close enough) and 4 degrees 975'.
DAPS pages 2-1 to 2-7 have gradients in %, the old IAL pages also had the gradient angle alongside the %. Still have mine in my DAPS, 3.5 degrees equals a 6.2% gradient, which can be read out from the Gradient to Rate table.
Starting at 3 degrees = 5.2%, and 6.6 degrees = 11.5%, each 0.1 degree = 0.2% increase, roughly.
Starting at 3 degrees = 5.2%, and 6.6 degrees = 11.5%, each 0.1 degree = 0.2% increase, roughly.
