Altitude 'errors'...

[Ken Hall 2]

W10; P3Dv5.3+; Radar Contact; LittleNavMap v2.8.12 (32bit), N2313; ASP3D + Cloud Art.

Radar Contact has been my must have addon for almost 20-years to the extent that i never fly without RC4 running!

Just recently I have been chastised unmercifully by ATC for not observing my 'given' altitude - this always associated with the descent phase of flight.

For example: descend to alt 9000ft - done - altitude 9000ft indicated on all instruments (including GoFlight MCPPro).

ATC keep calling me to stay with my assigned altitude - I am - warnings about being hauled in front of the FISDO and loosing licence.

I note that in the LNM map my aircraft is showing an altitude around 555 - 895 ft above 9000ft !!!🤕 despite all other indicators at 9000ft.

I have even changed my deviation to 1000ft in the General settings in RC4 - still receive warnings!

If I run P3D with only LNM the altitude numbers are correct at all levels - only when running RC4 am I having this 'fault'.

Am I missing something that I have not noticed/experienced previously?

Some 'assistance' would really, really be appreciated.

I have also posted this item on the LNM forum section.

Ken H.

 

 

 

Edited January 11 by Ken Hall

[Ray Proudfoot 8,976]

Ken,

I trust you have adjusted your MCP from STD back to QNH. But as you're a long time user I assume you've done that.

Don't change the Deviations. 15 for Heading; 300 for Altitude and 10 for Speed. You'll probably mess up the calculations with such large values.

Can you attach or paste a plan? Hard to evaluate without more info.

[IanHarrison 522]

I have experienced this a few times when I have accidentally changed STD to "live" QNH, thinking 10000' was in operation when actually it was much lower and I had been told to descend to a Flight Level lower than 10000'. But as Ray says, you are a long time user, so surely you would know?

Edited January 12 by IanHarrison
Spelling error

[Ray Proudfoot 8,976]

The rule is very simple. If instructed to an ALTITUDE you must be on QNH. If instructed to a flight level then STD must be engaged.

I have found a couple of rare instances when I know I’m at the correct altitude / FL when 40 miles out but have been told off. Descend 100ft and all is well.

Ken, what were the departure and arrival airports and your cruise altitude?

[Ken Hall 2]

Ray and Ian ~~~ thanks for your input.

Ray; flight plan was EDDB-TGL-DHE-SAB-EGPH at FL360.

I have reverted RC4 'deviations' as you suggested.

Descending to alt 9,000 feet I did change from Std to QNH (surprised at how high the figure was '1044.3' with AS running.

Will fly again today and report back 😎.

Ken H.

[Ray Proudfoot 8,976]

Ken, that’s Edinburgh so the TA is either 5000 or 6000ft. If you were instructed to descend to 9000 that should have been FL90.

I suspect part of the issue is high pressure over the UK. Switching from 1013 to 1044 is a massive change in displayed altitude on the altimeter. It requires a bit more planning.

Did you meet the crossing restriction at 40 miles out? I suspect you did as a long time user as that would still be on STD pressure.

[Ray Proudfoot 8,976]

My curiosity got the better of me as it's been a while since I landed in an area of very high pressure.

EGCC-EGPH B737-800 FL240. POL4S POL UN601 INPIP INPI1E

At 40DME out I was at FL120 at which point RC instructions take over.

I immediately reduced speed from 290kts down to 240kts and was given a heading to the airport. Soon after instructed to descent to FL80. That was followed by a right turn onto 065 and told to descend to 5,000ft QNH 1037. When pressing the BARO knob my altitude was 800ft higher at 5,800ft. That's a lot of altitude to lose hence the speed reduction.

Speed back to 230kts and followed by a left turn to 340 and down to 4,000ft. Then finally left onto 275 and down to 3,500ft for the localiser intercept.

When flying into areas of high pressure you need to lose speed as you have more altitude to lose.

 

[Ken Hall 2]

Good morning, Ray...

A very comprehensive response; thanks 😃.

Regarding my instruction to descend to 9000 feet (gives the QNH at same time) ~~~ this would seem to cantradict the TA!

Does RC use the TA as coded into RC (i.e. change to 'feet' as opposed to 'FL')

Whenever I receive "to feet" I have always changed from STD to QNH. Perhaps too early - wait for the co-pilot to check Baro at the TA?

Certainly an interesting 'can-of-worms' 😏.

Did you read the link that Alex gave regarding temperature/altitude deviations?

Has given me a new respect for the guys at the pointy end 😎.

Ken H

 

[Ray Proudfoot 8,976]

Hi Ken,

I suspect your m4.csv file may have a wrong value for the Transition Altitude for EGPH.

Go to your RC4\data folder and using Notepad (never Excel) open m4.csv.

Search for EGPH. It should show 1561,6000.

I'm unsure of the first value but the second is the TA. If it's 6000 then I'm stumped.

I did read that reply by Alex but I don't think it's relevant to your problem. If you were instructed to descend to 9000ft something is wrong with RC4 data files.

[Ken Hall 2]

Hi Ray,

just checked the m4.csv file and it is as your numbers show!

Made a flight EGSS - Vienna and monitored the altitude all the way!

Once above TA from Stansted the variations started with a difference between 'Indicated' and 'Altitude' of 350 - 480 feet.

Another 'interesting' challenge today was noted after crossing a VOR and changing frequencies for the next VOR the aircraft (freeware 777) started  'porpoising' with climbs of over 1000 feet then a drop to 600 - 800 below the planned FL350! Resulting in being shouted at by ATC with the offer of further help/training 🤐.

Holding the advised QNH until reaching the TA did make a difference with only an 'odd' 30 - 40 feet above the ground. That difference could be the reason why I have 'missed' the glide slope a few times recently 🤕 by being just a tad higher than necessary to pick up the beam!!!

All goods fun 😎.

 

[Ray Proudfoot 8,976]

@Ken Hall, for the Edinburgh arrival I would politely suggest you misheard the instruction.

For the other flight it doesn’t sound like a very good flight model. Time to invest in a better aircraft perhaps like the PMDG where I never have any porpoising effects.

[IanHarrison 522]

11 hours ago, Ray Proudfoot said:

@Ken Hall, for the Edinburgh arrival I would politely suggest you misheard the instruction.

For the other flight it doesn’t sound like a very good flight model. Time to invest in a better aircraft perhaps like the PMDG where I never have any porpoising effects.

Agreed. Porpoising is usually the result of a poor aircraft. Try re-installing first, just in case anything has become corrupted. If that doesn't help, then bite the bullet and get a PMDG or similar. My QOTSII doesn't do anything strange like that.

[FLSievert 0]

I've also been struggling with maintaining the assigned altitude above and below the TA. I noticed that when on the ground before asking for clearance, the weather briefing tells me QNH zero, zero, zero. Is that normal? I'm running on FSX-SE. I'll probably test it out with FSXWX to see if proper weather conditions will help the QNH values.

[Ken Hall 2]

Ray and Ian,

just been advised by my VA that the 777-200LF I downloaded from them is NOT compatible with P3D4/5.

Maybe the reason for mt recent difficulties ~~~ advice a bit late 🙄

Time to change aircraft for another run at the altitude variations!!!

Ken H.

[Ken Hall 2]

2 minutes ago, FLSievert said:

I've also been struggling with maintaining the assigned altitude above and below the TA. I noticed that when on the ground before asking for clearance, the weather briefing tells me QNH zero, zero, zero. Is that normal? I'm running on FSX-SE. I'll probably test it out with FSXWX to see if proper weather conditions will help the QNH values.

Hi! I run Active Sky (ASP3D) which, when loaded at my departure point, indicates the current/correct baro-pressure that is confirmed when receiving departure instructions from ATC.

My issue seems to be generated by an old, FS, model incompatible with P3D.

Lots of FSX aircraft are compatible with P3D. The 777F flight was a one-off so plenty of other models to choose from.

Ken H.