Takeoff and landing performance for the PMDG 737-800

Which PMDG 737 variants SkyNexus covers

PMDG sells the 737-600, -700, -800 and -900 for MSFS, each in passenger and some in business jet or freighter versions. SkyNexus has a model for the 737-800 and picks it when your SimBrief flight plan says B738.

• 737-800, passenger: the model is built for this one.
• 737-800 BBJ and freighters: you can file them as a B738 and use the numbers, but their weights and equipment differ, so treat the result with more care.
• 737-600, -700 and -900/-900ER: not supported yet. The 737 MAX is not supported either.

Assumed temperature and the derates

On the 737 there are two ways to take off with less than full thrust, and SkyNexus does both. A derate picks a lower rating: 26K is the full rating of the CFM56-7B26, 24K and 22K are the derates, each with its own V-speeds and its own minimum control speed on the ground. An assumed temperature reduces the thrust further on top of the rating you chose, up to the maximum assumed temperature Boeing publishes for your outside air temperature and pressure altitude.

Pick a rating and SkyNexus finds the highest assumed temperature at which every limit still holds: runway length, the engine-out climb, obstacles, brake energy and tyre speed. The rules do not allow an assumed temperature on a contaminated runway or when windshear is expected. Then use a fixed derate without an assumed temperature, or full thrust, and select it yourself.

Everything the CDU asks for

• V1, VR and V2 for flaps 1, 5, 10, 15 and 25, with V1(MCG) from the 737 QRH as the floor at 26K.
• OPTIMUM flap: every takeoff flap is checked and the one with the most runway margin wins.
• All three distances checked against TORA, TODA and ASDA, including intersection departures.
• The takeoff page laid out like the FMC, so you can copy it straight across.

The arrival, from the 737 QRH

VREF for flaps 15, 30 and 40 comes from the QRH table for your landing weight. You get the required landing distance with the regulatory margin, the distance you will really use with autobrake 1, 2, 3 or MAX, and the QRH landing distance next to it. Enter the runway condition code and the QRH braking action tables apply. Sixteen non-normal configurations, such as the loss of hydraulic system A or B or a landing with the flaps up, give you the approach speed and distance the checklist asks for. After landing, the QRH brake cooling schedule tells you how long the brakes need.

• More on the landing distance and the difference between the factored and unfactored number.

Why it can differ from the PMDG tablet

PMDG's tablet has its own performance calculator. Different tools can disagree by a few degrees or a few knots without either being wrong: the runway data, the weight you use, the obstacle check and how a wet runway is handled all move the result. SkyNexus uses the weight in your OFP, so if you change the load in the aircraft, update the OFP or type the new weight in. The help button next to every number shows the inputs and the limit that set it.

• Why takeoff calculators disagree explains each reason.
• The 737-800 performance page has the full list of what the model covers.

PMDG 737 performance FAQ

Does SkyNexus work with the PMDG 737?

Yes, with the 737-800. SkyNexus runs in your browser next to the sim and takes its inputs from your SimBrief flight plan, so it does not need anything from the aircraft. File the flight as a B738.

Does it do TO-1 and TO-2 derates?

Yes. The 24K and 22K ratings are the derates of the 26K CFM56-7B26, and SkyNexus computes V-speeds and the assumed temperature for each of them.

What about the PMDG 737-700 and 737-900?

Not yet. The 737-800 is the only 737 with a performance model today.

Is it free?

Yes. Create an account, enter your SimBrief Pilot ID and the performance tab is there for every 737-800 flight plan.

Is SkyNexus made by PMDG?

No. SkyNexus is an independent, free EFB and is not affiliated with PMDG.