PPRuNe Forums - PNR and Crit Point

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miles offtarget

2nd Jun 2004 00:05

PNR and Crit Point

Could someone please remind me of the simple formulae to determine single leg PNR and CP.

I remember that it is along the lines of E x H over O + H or something, but took ATPL Navs 6 years ago and don't have to engage the grey matter too often these days.

Thanks in advance.

Miles Offtarget

Thunderbug

2nd Jun 2004 07:31

Miles

Try This.......

T'Bug :ok:

ROB-x38

2nd Jun 2004 10:13

Simple straight line formulae:

PNR = (E.O.H.) / (O + H)

CP = (D.H) / (O + H) (gives distance from departure point (home) to CP)

E = endurance in hours
O = ground speed on
H = ground speed home
D = total distance

No_Speed_Restriction

2nd Jun 2004 11:04

Or if you want the full blown PNR Version:

Endurance / ((Sfc2Eng / Gs out 2Eng)+(Sfc1Eng / Gs home 1Eng))

:yuk:

miles offtarget

2nd Jun 2004 16:24

Thanks

Just what I needed. Bringing a Caravan across the pond this week so will be useful.

Thanks.

411A	4th Jun 2004 06:40

Was asked to do an assessment on a First Officer being upgraded to Captain some years ago, and as all the PNR/CP data was on the computer flight plan, asked him to compute the PNR/CP manually.
His answer was spot on, using the 'ole Jeppesen circular wizz-wheel.
Promotion approved.:ok: :ok:

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