Wind Correction on the HP48/50

Out of frustration with how slow working on an E6B can be during flight planning, I’ve been looking into electronic options for replacing it that do not involve buying an overpriced specialised calculator.

Whilst solutions like the CX-2 can be used in the US in exams, they can’t be used here, which defeats any benefit of using a type specific calculator over a more generic programmable.

Also, the pricing is such that a CX-2 costs about 2/3rd the price of a good programmable like the HP50G.

So I’ve opted to buy a 50G and implement as much of the E6B functionality as is practical for planning.

My initial efforts are as below!

Wind Correction on the HP50G (easily adapted to the non-CAS 48G by removing the →NUM instructions and the UNROT instructions with ROT ROT).

≪ 'curTAS' STO ≫ 'TAS' STO
≪ DUP curWHT - NEG curWV DUP2 WCA UNROT GS UNROT + →NUM SWAP →NUM ≫ 'TRKT' STO
≪ 'curWV' STO 'curWHT' STO ≫ 'WV' STO
≪ DUP2 WCA COS curTAS × UNROT SWAP COS × - ≫ 'GS' STO
≪ SWAP SIN × curTAS ÷ ASIN ≫ 'WCA' STO
{ TAS WV TRKT } MENU

These should all be put into their own folder. They work using globals to store values that carry over between specific operations.

It’s also written with RPN mode in mind. I’m not entirely sure how anybody gets anything done fast on a calculator using algebraic modes.

Oh, and set Degrees for angles unless you do your flight planning in Radians.

Using the above:

Change to the folder, and select the custom menu.

Punch in your TAS, press the TAS softkey.

Punch in your wind as two values – the heading and velocity – and press the WV softkey.

Punch in your desired track and press TRKT. The heading correcting for wind and ground speed will pushed onto the stack.

You only need enter a new WV or TAS if they change – they will persist between multiple TRKT operations.

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