altimeter settings in USSR

[L'Argonauta]

Which altimeter setting do you use when approaching an ex USSR Airport?

I was landing in Astana, below TL we decided to set Qfe at 4 Dme we were established and perfect VMC daylight the Egpws started to sound "TOO LOW TERRAIN", we disreguarded the warning and landed normally.

I reported it to my Tr.PH and he said that he had tha same warning when using Qfe because the EGPWS system works with altimeter setting and suggested me to use Qnh...

When you approach and land in Astana the ATC provide you with Qfe ( Qnh only on request ) but their clearances are issued in HEIGHTs ( example "descent to height 800 Qfe 998") so if you decide to use Qnh you have to do the maths by yourself to get the ALTITUDE ( height plus elevation ) and it's quite hard as long as you have to convert from meters to feets!!

[PicMas]

Disengage the terrain warning when approaching on QFE

[Son of a Beech]

According to my humble upinion the GPWS Mode 4 (A/B) callout "to low terrain" is a result of to high speed at to low RAD ALT not BARO ALT.

explaned mode 4(A/B)

4A - Unsafe Terrain Clearance With Landing Gear Not Down
This is the terrain clearance mode with the gear retracted, is armed after take off upon climbing through 700 ft radio altitude. When this envelope is penetrated at less than 0.35 mach the aural alert TOO LOW, GEAR is sounded. When the envelope is penetrated at more than 0.35 mach, the aural alert TOO LOW TERRAIN is sounded and the upper boundary of the envelope is increased to 1000 ft rad alt. The message is repeated until the flight condition has been corrected.

4B - Unsafe Terrain Clearance With The Flaps Not In Landing Position
This mode provides an alert when the gear is down and the flaps are not in landing position. If the envelope is penetrated at less than 0.28 mach with the flaps not in the landing position, the aural alert TOO LOW FLAPS is sounded. When the envelope is penetrated at more than 0.28 mach, the aural alert of TOO LOW TERRAIN is sounded and the upper boundary is increased to 1000 ft rad alt. The voice messages continue to occur until the flight condition has been corrected.
The TOO LOW GEAR alert take priority over TOO LOW FLAPS. The TOO LOW FLAPS and associated TOO LOW TERRAIN alert are inhibited with the flap inhibit switch when moved to the FLAP INHIBIT position

P.S trigger speeds may vary with aircraft type

[alkor]

exactly.

DO NOT disengage GPWS.

cheers,
a

[L'Argonauta]

What if you are in IMC? I think disengaging Egpws is not a good idea...I posted the same question on Tech Forum and many runers told me that even their planes have problems on EGPWS using QFE...so i think i have to do the maths!!

!

[macjet]

QFE ops

- Which plane do you fly?
- Is the EGPWS software up to the latest revision?

Disengaging the itself capable system is not a good idea - Pilots doing the math is even worse...

mJ

[H.Finn]

Flown in the former USSR for as long as GPWS and EGPWS have been around, always used QFE and never had any warnings. Exceptions being arports which are not included in the EGPWS database, that is airports where you will have to use a local navigator to supply charts and act as an interpreter for ATC.

[Romasik]

Well, with GPWS it's clear - it's a dumb thing that only reacts on your radio altitude, configuration and speed. As for EGPWS - it's a different beast which uses terrain database with terrain elevation measured from MSL. Whatever your atimeter setting, it thinks it's QNH, and gets upset when you are actually on a perfect glideslope at a more or less elevated airport. So, use QNH and do your math. Disabling EGPWS is a bad idea, especially in IMC.

[Lazy Bird]

Ussr / Egpws

I agree with H.Finn.
we had troubles with terrain warning using QFE on few airports only.
Usually a call to Honeywell solves your problem after the next database update!
As you know, flying in russia might keep you busy, (seldom flights to russia, language, navaids, procedures, young collegues.......) then good luck on your maths. What is the higher risk if you are well prepared??

Let them spend the money and provide us with well consistent databases!

[theloveman72]

Talking altimeter setting in Russia. Any of you know if ATC will provide descent altitude corrected for low altimer/low temperature ?

I have heard that somewhere but i want to confirm it. It may be not usefull in Moscow but if you land in Petropavlosk (UHPP), with basic radar, that volcano gets very close if you have a bad altimeter setting.

[Red Goose]

Our company policy is to use QFE when flying in the CIS. And I think it is a good idea, as it allows less room for error, either from the controller converting QFE to QNH, or from me readind the wrong altitude on the Jeppesen chart conversion table ( if I am cleared to 600m height, and I read 2600ft (QNH) instead of 1920 ft (QFE), at least I am on the safe side). Previous example is for an airport at an elevation of 680 ft (Moscow UUWW).
If your FMS software is not adapted to QFE, you will get a terrain warning on approach when you reach the field elevation (i.e 680ft in Moscow UUWW), if you are flying in QFE. If that is your FMS condition , it might be better to fly QNH...

[galaxy flyer]

It depends a bit on where your EGPWS is getting its position information and is it "enabled". In the Honeywell and R-C systems I fly, if you leave the GPS enabled, the EGPWS should work fine, if the airport in the database and the DB is up-to-date, regardless of QFE or QNH. The EGPWS works off of GPS and WGS-84 which is the datum that the DB elevation and obstacle information is formatted.

However, you cannot use VNAV or FMS approach in QFE operations due to incompatible altitude information. You must fly approaches in raw data.

If the FMS enters landing elevation for pressurization, it needs to be put in Manual and a manual elevation of Zero entered.

It would be easier if we could enter "0" in the FMS landing elevation, all would be well.

You must turn off TERRAIN, if you have disabled the GPS receivers, btw. Because the EGPWS has no GPS positional information to work with.

GF

[PicMas]

I still maintain that if:

The controller is used to give altitudes based on QFE, the pilots should set QFE to avoid pilot and controller error in the conversion - as posted above.
The controller may very well agree to give QNH, and may correctly do so, if there is a handover or the controller looks at his scope and sees you entering a certain sector for the approach, there is a minute chance he will pass the same (QFE-based) altitude as for the previous 1,000,000 aircrafts, a well-known scenario for error based on law of recency.

In that case if:

The gadgetgizmo gives you warnings, and there is no sensible way to correct this ie. update database etc, the warning feature should be disconnected. The gadget - whatever it is - is not what is keeping the aircraft from hitting the ground. There are, for most Russian installations, two NDBs with corresponding altitudes, DME, timing and of course a glideslope or an AZELscope.

My vote is still for:

Fly QFE - to avoid conversion workload (this may already be increased due to conversion from meters to feet) and habitual clearances from ATC.

Disconnect known warning - The idea of ignoring a warning (if it can not be corrected).... no need to discuss that one I think.

The EGPWS is there to, among other things, warn about altitude being too low for a particular segment of flight, if it is known prior that this function is not performing as intended it should be disconnected. When it, on short final to Vnukovo, gives the TOO LOW TERRAIN warning this is incorrect.

[ahramin]

Not all EGPWSs use radar altitude.

[Son of a Beech]

Not all EGPWSs use radar altitude.

Mode 4 does, use RADALT

for the rest EGPWS uses geomatric altitude:

Geometric Altitude is a computed aircraft altitude designed to help ensure optimal operation of the EGPWS Terrain Awareness and Display functions through all phases of flight and atmospheric conditions. Geometric Altitude uses an improved pressure altitude calculation, GPS Altitude, Radio Altitude, and Terrain and Runway elevation data to reduce or eliminate errors potentially induced in Corrected Barometric Altitude by temperature extremes, non-standard altitude conditions, and altimeter miss-sets. Geometric Altitude also allows continuous EGPWS operations in QFE environments without custom inputs or special procedures by the flight crew when operating in a QFE environment. Required Inputs for Geometric Altitude The Geometric Altitude computation requires GPS Altitude with Vertical Figure of Merit (VFOM) and RAIM failure indication along with Standard (Uncorrected) Altitude and Radio Altitude. Ground Speed, Roll Angle, and Position (Latitude and Longitude) are used indirectly and are also required. Additionally, Corrected Barometric Altitude, Static Air Temperature (SAT), GPS Operational Mode and the Number of
Satellites Tracked are used if available. The required GPS signals can be provided directly from an external ARINC 743 / 743A receiver or from
the optional internal EGPWS Xpress GPS Receiver card. Standard Altitude, Corrected Barometric Altitude, and Static Air Temperature (SAT) are provided directly from the ADC. If SAT is not available, geometric altitude is computed using Standard Altitude with a corresponding reduction in accuracy.

Remember: The whole point of EGPWS and GPWS is based on warning the pilot for the mistakes a pilot made!!

SOAB

[galaxy flyer]

SOAB

Thanks for the very complete answer on how EGPWS gets its positional information and I agree except:

If an FMS uses GPS positional information for FMS Approach, in non-WGS-84 airspace, one must disable the GPS receivers and use DME-DME FMS information for FMS Approach or go Raw Data. GPS cannot be used for approach navigation in non-WGS-84 locales. Yes, the EGPWS works fine with GPS in non-WGS-84 airspace for warnings. Be careful about datums and the CIS isn't about to change to WGS-84.

GF

[ahramin]

Galaxy flyer, instead of disabling the GPS inputs, why not get the navdata for the datum used in that airspace and use that datum?

Quote:
Not all EGPWSs use radar altitude.
Mode 4 does, use RADALT

Class B TAWS are specifically not required to have RADALT. Mode 4 is accomplished through using takeoff elevation when RADALT is not available.

Relationship between GPWS and FLTA

FLTA produces alerts from things ahead of the airplane using a terrain database, GPS position, velocity, etc. GPWS produces alerts from things underneath the airplane and alerts from configuration, such as excessive descent rates while close to the ground, gear and flap warnings during landing, etc.
The FLTA features in Class A and Class B are identical and represent the same level of safety. The main difference is in the GPWS portion of the system. Class A requires a "fully autonomous" GPWS while Class B does not. The practical effect of this means:

• Class A requires Radar Altitude and Class B does not.
• Class A requires Airdata and Class B does not.
• Class A requires both Gear/Flap inputs and Class B does not.
• Class A requires an STC and Class B does not. (Money and time!)
• Class A requires a map display and Class B does not.

This does not mean, however, that a Class B lacks all the GPWS features. Instead, what was done in the regulation was to specify a minimum feature set in Class B which could be implemented by substituting "synthetic radar altitude" derived from the terrain database and GPS altitude to allow most of the GPWS alerting functions. Class B GPWS alerts are not autonomous, because failure of the GPS receiver will fail both FLTA and GPWS. In a Class A system failure of GPS will not fail the GPWS.

[Lear Jockey]

We had the same warnings. I suggest you keep the EGPWS on and don't, never, appart from flying into known mountainuous area and being VMC, shut it off!

If you quickly have a look on the Jepp charts, you'll find [B]both[B] QFE and QNH altitudes written on the side of the charts, STAR's, approach and even SID's. The matter is to have a look at the field elevation, convert it with the QFE given into QNH (add 1 hPa per 30 feet of elevation). When first contacting approach, ask them for QNH and compare with what you have. It is usually within 1 hPa anyway.
Then when ATC clears you to and altitude in meters QFE, you don't care, you compare the meters into the QNH on you Jepp chart and that's no more calculation!
Have a good flight!

[PicMas]

So you had the warnings? What did you do? continue?

I dont think anybody suggested turning off the EGPWS - Just the terrain warning.
What you suggest adds an extra step in each stepped descend, which basically means an extra opportunity to get it wrong for each descend clearance.

[jetopa]

No more USSR...

Exactly! Fly the f...cking aircraft.

And one more thing: the 'USSR' ceased to exist in the 90s. It's either 'Commonwealth of Independent States' (CIS) or simply Russia, Kasachstan, Ukraine etc...

Last time I heard, the people there highly appreciate not to be called 'Soviets'.