‘naturally’ the minimum vertical separation minima of 1000 feet, this crossing point is unsatisfactory.
The above does not suggest that aircraft climb performance is the only factor to be considered in determining the vertical distance between the aircraft at the crossing point. Neither should it suggest that 1000 feet is the minimum vertical separation to be applied at all crossing points. On the contrary, designers and planners should take various other factors into account in the determination of the vertical distance between the aircraft at the crossing point. These include :
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History of level busts: where applicable. (Mitigation might include publishing level restrictions which ensure 2000 feet between the climbing and departing aircraft at the crossing point);

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Nuisance ACAS alerts: an appreciation of how ACAS Traffic and Resolution Advisories may be triggered by route geometry. (For information on ACAS ‘hotspots’ and ACAS safety information, see ACAS Safety Bulletin 11 of July 2002;

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Low Transition Altitude: Experience has shown that requiring climbing aircraft to stop their climb at or in the vicinity of a low Transition Altitude may increase the likelihood of level busts. The same may be true of arriving aircraft as regards the Transition level.

Arrival 
 
30NM from Touchdown 
Departure7NM from Take-Off R1.2 (Graph 5-1)  R1.2 (Graph 5-1) 

Figure 5- 8: ApplicationR1.2 (&R1.1)

RNAV is all about point-to-point navigation; why is it necessary to design the downwind legof RNAV STARs close to the runway (as per R1.2/Figure 5- 8)? R1.2 concerns finding the most suitable crossing point between an arrival and departure route so as to restrict, to the minimum, the vertical profile of the crossing aircraft. The application of RNAV does not change the desirability of applying R1.2. Although users sometimes react adversely to the realisation that RNAV has not served to reduce track mileage in this instance, they usually react positively to the freer aircraft profiles. 
What are the alternatives to designing a downwind as per R1.2/Figure 5- 8? This question arises where the downwind as shown not be designed either because of noise sensitive areas close to the airport or where the richness of terrain makes such design impossible. Fortunately, alternatives do exist especially if a robust &detailed equivalent of Graph 5-1is custom made for a Terminal Airspace. If this graph is developed with the assistance of pilots, it should provide a greater spread of descent/climb profiles which may provide alternative which include – . RE-locating the SID/STAR crossing points whilst respecting R1.2, if possible (e.g the SID could continue on runway heading for a greater distance); . raising the climb/descent level restrictions at the crossing point shown in Figure 5- 8; . permitting only ‘quieter’ aircraft to fly on the SID/STAR shown in Figure 5- 8(these aircraft would be identified as a combined function of Graph 5-1 and data collected from noise monitoring points in the vicinity of the airport) 

1 http://www.eurocontrol.int/acas/LatestNews.html
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0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000 24000 26000 28000 30000 32000 34000 36000 T/0 3 ALTITUDE ABOVE MSL 60 57  SAMPLE ARRIVAL/DEPARTURE PROFILES (Aerodrome Elevation at M.S.L) 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 DISTANCE FROM TAKE-OFF IN NM 54 51 48 45 42 39 36 33 30 27 24 21 18 15 12 DISTANCE TO TOUCHDOWN IN NM  51 54 57 60 9 6 3 T/D 
　
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本文鏈接地址：EUROCONTROL MANUAL FOR AIRSPACE PLANNING 2(41)