g200 max efficiency

Maximizing Fuel Efficiency and Range

Brett Rundle

• Specific Range is the number of nautical miles traveled per pound of fuel burned

• Maximizing fuel efficiency and range is important to many operators trying to achieve a long range flight, or operate the aircraft at maximum efficiency due to increasing fuel costs

• In order to get the most fuel efficiency and range, an aircraft must be flown at an angle of attack that results in the highest Specific Range

Specific RangeSpecific Range

How do I achieve the best Specific Range?How do I achieve the best Specific Range?

• You must fly the aircraft at an altitude and air speed that results in an angle of attack that produces the best lift to drag ratio

• This combination of altitude and speed constantly changes throughout the flight as the weight of the aircraft decreases due to fuel burn

General Rules of ThumbGeneral Rules of Thumb

• The heavier your aircraft is, the lower the altitude that must be flown for maximum efficiency

• The heavier the aircraft is, the faster the airspeed that must be flown for maximum efficiency (if a constant flight level is flown)

• Generally, you should fly faster with a headwind component and slower with a tailwind component to maximize Specific Range

• Temperature deviations from ISA, when maintaining a given mach number, will not affect Specific Range, since fuel flow increases or decreases in the same proportion as true airspeed

Operational Planning Manual (OPM)Operational Planning Manual (OPM)

• On a flight which tries to achieve maximum efficiency and range, the aircraft would start at a lower initial cruise and climb as weight decreases

• This would result in the wing being at the most efficient angle of attack throughout the flight

• A common mistake made by pilots is the thought that “we need to get as high as possible to achieve a lower fuel flow”. Although this may produce a lower fuel flow, it also produces a lower Specific Range initially

• The best source is the OPERATIONAL PLANNING MANUAL

G150 Operational Planning ManualG150 Operational Planning Manual

The OPM is available in hard copy, or electronically as a part of PlaneBook

G200 Operational Planning ManualG200 Operational Planning Manual

The OPM contains data for

• Climb Performance

• Long Range Cruise

• Constant Speed Cruise

• Normal Maximum Cruise

• High Maximum Cruise

• Single Engine Operation

• Descent

• Holding

G150 OPM – Long Range CruiseG150 OPM – Long Range Cruise

One of the best pages in the OPM (and least referenced) is found in the beginning of Section III –LONG RANGE CRUISE


It shows a chart calledOPTIMUM ALTITUDE FOR LONG RANGE CRUISE

On this chart it is clear to see the relationship between weight and optimum altitude


For example, on a G200 departing at maximum take off weight, the optimum altitude after one hour of flight would be about 34,000ft


At mid-weight, the optimum altitude would be approximately 38,000ft, and towards the end of the mission it would be 41,000ft

Long Range CruiseLong Range Cruise

• Assuming International Standard Atmosphere (ISA) 0 temps, this equates to an initial Specific Range of .234, a mid - weight Specific Range of .287 and a final Specific Range of about .319 (nautical miles/pound of fuel)

NOTE: This can be checked real-time in the aircraft to compare against book data by referencing FMS (FUEL MANAGEMENT) page 1/3


On a G150 the optimum altitude after one hour of flight would be about 39,000ft due to the lower wing loading of the aircraft


At mid-weight, the optimum altitude would be about 43,000ft and towards the end of the mission it would be almost 45,000ft

Long Range CruiseLong Range Cruise

• Assuming International Standard Atmosphere (ISA) 0 temps, this equates to an initial Specific Range of .322, a mid – weight Specific Range of .383 and a final Specific Range of about .421 (nautical miles/pound of fuel)

NOTE: This can be checked real-time in the aircraft to compare against book data by referencing FMS (FUEL MANAGEMENT) page 1/3

Constant Speed CruiseConstant Speed Cruise

• Because it is usually impractical to fly a profile with a constantly changing airspeed and altitude, most operators will fly a constant mach number which is the average speed that is most efficient

• This speed for both the G200 and G150 is mach .75

• When a constant mach is flown, it is best to climb in steps that overlap the Optimum Altitude For Long Range Cruise

• This reduces the need to continuously reference the OPM throughout the entire flight

• The data for this is in Chapter IV of the OPM (CONSTANT SPEED CRUISE)

• Data in Chapter IV is presented in tabular format showing several speeds for a given Flight Level along with different temperatures and the resulting fuel flow and specific range

Constant Speed CruiseConstant Speed Cruise

ATC RestrictionsATC Restrictions

• “What if ATC holds me at an altitude and I cannot climb?”

• In this scenario, speed would need to be decreased as aircraft weight decreases in order to keep the wing at the optimum angle of attack

• For example, if ATC holds you at FL370 and temp is ISA 0, initial speed on a G200 is .77Mi and ends up at .68Mi

• On a G150 in the same situation initial speed is .72Mi and ends up at .60Mi

You must reference the OPM for optimum numbers under current conditions of weight and temperature

Too High, Too SoonToo High, Too Soon

• As stated earlier, a common mistake made by many pilots is climbing too high, too soon

• This results in the angle of attack being not only less efficient, but also closer to the stalling Angle of Attack (AOA)

• Although fuel flow is lower, the aircraft will get less specific range with a lower margin above stall in case temperature increases or turbulence is encountered

COMMON DURING OCEANIC CROSSINGS!

Notes of InterestNotes of Interest

• G200 climb profile (above 10,000ft)Normal Data – 250 KIAS to .75 MiHigh Speed – 290 KIAS to .78 Mi

• G150 climb profile (above 10,000ft)Normal Data – 210 KIAS to .70 MiHigh Speed – 250 KIAS to .75 Mi


• Although predictive performance data is now available in the FMS for both G200 and G150, there are some important things to know– Performance data in the FMS is “advisory” only.

The AFM and OPM must be referenced for fully “approved” data

– The G200 performance data is stored in 10 degree increments due to limitations in database size. This will cause “UNABLE CRZ ALT” to be displayed on the FMS when you may actually be able to achieve that altitude. (Refer to the OPM)

– The G150 data is stored in 2 degree increments and should be more accurate as a result


• The PREDICTED mode of the FMS is a great tool to use to know how much fuel you will have at your destination and alternate

• Remember: GARBAGE IN = GARBAGE OUT!• Put accurate data on the PERF INIT page and

DEFAULTS• Fly as closely to the FMS stored profile as possible

including climb and descent• Uplink your Flight Plan AND Flight Plan Winds!

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g200 max efficiency

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