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Joined: Thu May 30, 2002 6:30 am

Step Climbs And Vertical Separation Over Pacific

Sun Jul 30, 2006 4:24 am

I recently returned to Australia on UAL 839, LAX-SSY on a 744. We started out cruising at FL290 and I noticed that as we progressed, the step climbs were in 500 foot increments (FL295, FL300, etc.) resulting in a final cruise altitude of FL370 at the top of descent point into Sydney. Are the track rules over the Pacific different than the Atlantic or have the vertical separation rules over remote areas changed?
Troy - UAL787
Posts: 4196
Joined: Mon Jan 31, 2005 5:11 am

RE: Step Climbs And Vertical Separation Over Pacific

Sun Jul 30, 2006 6:42 am

What you are describing is not a step climb but the simplification of an ascending cruise.
In order to optimize his flight, a pilot can elect,when flying outside designated ATS routes over oceanic regions to adhere the closest to the optimim altitude his/her aircraft is capable.
With a modern FMS which constantly computes the optimum altitude, depending on the cost index or the regome to fly (long range for instance...), the exercise is rather easy and fun : on a 744, youd climb 100 ft every 5 or 6 minutes.
Of coiurse that flight has to be protected from other traffic, therefore some sort of lateral protection is awarded (We do it as a routine between LAX and PPT), and a specific flight ploan has to be filed .
ATC services would in this case require
1/- the way point at which the ascending cruise would begin,
2/- the cruising mach number and
3/- the blocked slice of altitudes to be reserved for the flight.
On a flight plan, it would show thus :C/25N125W/M085F300F380, meaning that we intend an ascending cruise (denoted by the C/ ) from the point 25 North 125 West with a cruising Mach of .85 and we'd like to block the airspace between levels 300 and 380.
Sometimes when the winds aloft are favorable, the final level is not mentioned and the last part of the FPL would then be :...F300PLUS, but I saw that example only once in my career.
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