OMA Section 8.1 Flashcards
What are the differences between a Primary and Secondary alternate aerodrome?
Unlike Primary alternates, Secondary alternates have only basic ground handling facilities and passenger handling is not assured.
What is the relevance of seeing an alternate aerodrome on the aircraft specific LIDO en-route chart?
This aerodrome is an approved alternate.
How is it possible to determine if a runway is approved for use by BA aircraft?
Operations Manual Part B (Dispatch Performance Data Manual) lists runways approved for use for non EFB fleets.
For EFB fleets, runways listed in the application performance database are approved.
When is a take-off alternate required?
When it would not be possible to return to the aerodrome of departure for met or performance reasons based on the weather conditions at the time of departure.
Where must the alternate departure aerodrome be located?
Within:
- For 2 engined aeroplanes - 60 minutes
- For 3/4 engined aeroplanes - 120 minutes
- For ETOPS aeroplanes - 120 minutes or the ETOPS rule time if less (except the USA and Saudia Arabia)
When is a destination alternate not required?
- The flight duration does not exceed 6 hours
- The destination has 2 separate runways available and useable with met conditions +/-1 hour of ETA
- Ceiling 2000ft agl or circling minima + 500ft
- Ground visibility is at least 5K
When does BA plan for a destination alternate?
It is BA policy to always plan for a destination alternate.
When are two destination alternates planned?
- When there is no met data available for the destination.
- When the appropriate forecasts for ETA +/- 1 hour are below planning minima.
What are the differences between a fuel alternate and a commercial alternate?
- A fuel alternate is nominated when the conditions at destination are such that a diversion is considered unlikely. It may have limited facilities.
- A commercial alternate is considered at the flight planning stage. It has better facilities including those to handle passengers.
What is the application time period for the initial part of a TAF?
From the start of the initial part of the validity period to the applicable time of the first FM or BCMG. If there is no FM or BCMG then until the end of the TAF validity.
How is the TAF forecast applied?
The initial part of the forecast is fully applied (time period) except for ‘mean wind’ or gusts.
In a TAF, what changes are considered from the beginning of a change period?
If these changes are within +/- 1 hour of ETA of the considered aerodrome then consider:
- FM
- BECM AT
- BECMG (deterioration)
- BECMG FM (deterioration)
- BEMG TL(deterioration)
- BECMG FM…..TL(deterioration)
Mean wind applied
Gusts disregarded
In a TAF, which changes are considered from the end of a change time range?
If these changes are within +/- 1 hour of ETA of the considered aerodrome then consider:
- BCMG (improvement)
- BCMG FM (improvement)
- BCMG TL (improvement)
- BCMG FM-TL (improvement)
Mean wind applied
Gusts disregarded
In a TAF, how are transient/change conditions considered? (e.g. thunderstorms, showers)
- TEMPO
- TEMPO FM
- TEMPO FM - TL
- PROB 30/40
These changes are not applicable to deteriorating conditions.
Mean wind and gusts: exceeding required limits may be disregarded.
In a TAF, how are persistent conditions considered? (e.g. haze, mist, fog, dust/sandstorm continuous precipitations)
- TEMPO
- TEMPO FM - TIL
- TEMPO FM
- PROB 30/40
These conditions are applicable to deteriorating conditions.
Mean wind should be within limits.
Gusts may be disregarded.
In a TAF, how are the following change notifiers considered with respect to an improvement in conditions?
- TEMPO
- TEMPO FM - TL
- TEMPO FM
- PROB 30/40
They should be disregarded.
In a TAF, how are the changes notified as ‘PROB’ and ‘TEMPO’ considered?
For deteriorating conditions, changes may be disregarded.
For improving conditions, changes should be disregarded.
How does TAF application change with respect to an ETOPS en-route alternate?
Mean winds should be within required limits.
Gusts exceeding cross wind limits should be fully applied.
What is the bandwidth used for calculatinfg the MSA along flight plan tracks?
Generally 20nm on each side of track but potentially 10nm and 5nm can be used.
What is the minimum MSA published on CIRRUS flight plans?
2000ft
What does MGA indicate?
Minimum Grid Altitude (MGA). MGA shows the lowest safe altitude which may be flown off-track. MGA is calculated by LIDO by rounding up the elevation of the highest obstruction within the respective grid area and adding an increment of:
- 1000 ft for terrain or obstructions up to 6000 ft; or
- 2000 ft for terrain or obstructions above 6000 ft.
When is indicated by an MGA in purple?
MGAs in purple are those below 10,000ft.
What is indicated by an MGA in red?
MGS in red appear when they are at or above 10000ft
What are MTCAs and what do they mean?
Minimum Terrain Clearance Altitude (MTCA). MTCA covers, exclusively, terrain and obstacles relevant for air navigation. For SIDs and STARs, the MTCA is calculated by LIDO for an area 5 NM either side of the procedure centreline, and around a NAVAID or waypoint. For airways the buffering extends to 10 NM either side of the centreline. MTCA is calculated by rounding up the elevation of the highest obstruction within the respective area and adding an increment of:
1000 ft for terrain or obstructions up to 6000 ft; or
2000 ft for terrain or obstructions above 6000 ft.
