Figure C - 3: ITP volume
Figure C - 3 illustrates the ITP volume for an ITP climb.
The ITP maneuver is vertically limited to 4 000 ft (+ 4 000 ft in climb, - 4 000 ft in descent). Therefore, Reference Aircraft may be between 1 000 and 3 000 ft above (in climb) or below (in descent) the cruise flight level. Refer to Figure C - 4.
+4 000 ft +3 000 ft +2 000 ft +1 000 ft
CRZ FL
-1 000 ft -2 000 ft -3 000 ft -4 000 ft
= Reference Aircraft
= Other aircraft
Figure C - 4: Side view of ITP volume
C.2.4. ITP GEOMETRIES
The maximum number of Reference Aircraft is limited to two. Reference Aircraft are at any flight levels between the initial and the desired flight levels. The following illustrations describe some ITP geometries. Other geometries refer to two Reference Aircraft that are both behind or both ahead of the ITP Aircraft.
ITP climb BEHIND ITP climb AHEAD OF ITP climb BEHIND/AHEAD OF
BEHIND/AHEAD OF Figure C - 5: ITP geometries
C.2.5. ITP DISTANCE
The ITP distance is the difference of distance to a common point along tracks of ITP and Reference Aircraft. Refer to Figure C - 6. Figure C - 7 provides the calculation methods of the ITP distance for different geometries. For more details, refer to ICAO PANS-ATM, Doc 4444, Chapter 5
– Separations Methods and Minima (see References).
The ADS-B distance computed thanks to ADS-B information is the distance between the GPS positions of both aircraft.
The TCAS range is the distance computed by TCAS between the current aircraft positions.
Note: It has to be noted that aircraft are separated by thousands of feet vertically and dozens of nautical miles horizontally. As a rough order of magnitude: 1 000 ft
10 NM
Figure C - 7: ITP distances with different geometries
C.2.6. ITP CRITERIA
To ensure that the ITP Aircraft and the Reference Aircraft do not get closer than the ITP separation minimum (10 NM), the following conditions must be met.
-Able to make a climb AHEAD OF. The ITP distance exceeds the minimum
-Not able to make a descent BEHIND. The ITP distance is less than required.
C.3. EXAMPLE
The following sections describe the ITP step by step from a cockpit perspective. In any cases, refer to AIP.
C.3.1. PF: CHECK THE AIRCRAFT PERFORMANCES
When the flight crew decides a FL change, PF checks the aircraft performances on MCDU FMS PROG page.
When the aircraft is below the REC MAX FL, the aircraft is able to:
-Climb at 300 ft/min minimum
-Maintain its speed during the climb. Figure C - 8: MCDU PROG page
C.3.2. PF: INITIATE THE ITP
In the MCDU MENU, PF selects TRAF (LSK 5R in Figure C – 9) to display the TRAFFIC LIST page. In the TRAFFIC LIST page, PF selects IN TRAIL PROCEDURE (LSK 5R in Figure C – 10) to display the ITP TRAFFIC LIST page.
In the ITP TRAFFIC LIST, PF enters the desired FL in the DESIRED FL field (LSK 1L in Figure C - 11).
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