View Full Version : Civilian Safety Altitude Calculations

Been There...
15th Dec 2006, 11:35
I wonder if someone with experience of flying in France (or anywhere else in Europe) can explain how they calculate their safety altitude from a given MEF on a flight chart.

I am involved in a military project trying to define a SALT corridor within an FMS. The french civilian FTE reckons the French do not have a stepped margin eg RAF rules 0-3000ft, add 1000ft, 3001+ add 2000ft but rather they just have one value for all terrain. In true French-British fashion I don't believe him :) as it seems weird that the UK (Mil and Civilian), US and Canadians all have stepped values and they (the French) don't.

Can anyone shed any light on this matter or point me in the direction of somewhere I can find the EASA (or national) regs for this?


15th Dec 2006, 18:24
This help?

Been There...
15th Dec 2006, 19:10
Excellent, provides the information I was looking for.

IFR Mininum Level ...when no minimum level is specified, at a level of at least 300 m (1000 ft) above the highest obstacle located within a radius of 8 km around the estimated position of the aircraft. This value is set to 600 m (2000 ft) in hilly or mountain areas.

Thanks and kind regards

15th Dec 2006, 19:44
The other place to find info is here: JAR OPS-1 IEM OPS 1.250

Sorry can't post link as we pay a lot of money for our subscription, but hopefully you can access it somewhere.

For info, EASA does not regulate Ops or FCL stuff yet, but it's coming.

Been There...
15th Dec 2006, 20:10
I will have a look at work on monday and see if we have a copy that we can access. However, I know the French guy will have a copy of that.


20th Apr 2009, 18:57
All, hope you can help with me with this.

Rather than create a new thread, I found this one to carry on the discussion regarding safety altitude.

Can anyone confirm the following:

1) Do civilian Approach Plates (jeppesen, Navtech and also US DOD plates in particular here) use 1000' or 2000' on elevations to generate safety altitude for terrain above 3000' AMSL? Having read JAR-OPS, it appears 2000' is only added for terrain above 6000'? Is this the case?

2) Which regs do Civvy plate publishers use to create minima? I am guesing JAR OPS and the American equivalent.

THanks in Advance!

Edit, just found this in PANS-OPS

8.1.1 Minimum sector altitudes shall be established for each aerodrome where instrument approach procedures
have been established. Each minimum sector altitude shall be calculated by:
a) taking the highest elevation in the sector concerned;
b) adding a clearance of at least 300 m (1 000 ft); and
c) rounding the resulting value up to the next higher 50-m or 100-ft increment, as appropriate.
8.1.2 If the difference between sector altitudes is insignificant (i.e. in the order of 100 m or 300 ft as appropriate)
a minimum altitude applicable to all sectors may be established.
8.1.3 A minimum altitude shall apply within a radius of 46 km (25 NM) of the homing facility on which the
instrument approach is based. The minimum obstacle clearance when flying over mountainous areas should be
increased by as much as 300 m (1 000 ft).Sounds to me as if plates manufactured according to PANS-OPS only give you 1000' separation, in contravention of JAR-OPS which state 2000' to be added for terrain above 6000'!!!

Now confused :uhoh:

20th Apr 2009, 22:25
PANS OPS allows for increases in MOC of up to 100% in "mountainous areas".
"Mountainous area" is defined as an area of changing terrain profile where the changes of terrain elevation exceed 900m (3000ft) within a distance of 18.5km (10NM).

So, terrain over 3000ft does not automatically qualify as a "mountainous area" and an increase in MOC. However, some countries may well choose their own definition, or simply define the areas.

PANS OPS is an ICAO manual, and does not have the same status as Standards & Recommended Practices. It can't really 'contravene' any locally developed documentation.

21st Apr 2009, 07:25
A couple of points...

JAR-OPS is a minimum standard for operating procedures for specific types of aircraft operation. PANS-OPS is, in this case, a design standard. There is no reason that an operating procedure should not demand a greater margin of safety - or whatever - than the design standard provides.

Also, surely the definitive documents for approach plates is the State AIP. In theory Jepps and Navtech should simply reproduce the AIP - but sometimes don't!

21st Apr 2009, 09:04
cheers all.

Anyone know if the likes of jeppy and navtech have their own standard rules regarding Minimum sector altitudes, or do they simply stick to the National AIP for the country in which the plates are being manufactured?

5th May 2009, 01:10
Jeppesen merely reproduce the information from the source AIP

5th May 2009, 10:35
... which is the reason you see so many altitude standards in Jeps - MOCAs, MORAs, MEAs etc. etc. and their associated annotations on the charts.

As an example: An altitude on the chart annotated with a "T" (mnemonic - you are Trusting the state's rules) means that the altitude provides terrain clearance of either: plus or minus 10 miles, or 5 miles or 12.5 degrees out to 30 miles, surrounded by a 5 mile buffer - all depending on the state you are flying in.