What are Boeing 737-800 V-speeds, and how are they calculated?
Learn what Boeing 737-800 V1, VR, V2 and VREF mean, which inputs change them, and how crews and simulator pilots calculate valid speeds.
Boeing 737-800 V-speeds are not fixed numbers. V1 is the take-off decision speed, VR is rotation speed, V2 is take-off safety speed, and VREF is landing reference speed. Approved performance data or software calculates them from aircraft weight, flap setting, runway conditions, weather, thrust setting and operational constraints.
Boeing 737-800 V-speed definitions
The main 737-800 V-speeds identify specific points during take-off and landing, and all are expressed as indicated airspeed in knots.
| Speed | Meaning | How it is used |
|---|---|---|
| V1 | Take-off decision speed | The first action to stop must begin by V1 for the calculated accelerate-stop performance to apply. After V1, an engine failure normally results in continuing the take-off. |
| VR | Rotation speed | The pilot begins raising the nose at VR. It is calculated to produce a safe lift-off while respecting control, geometry and certification limits. |
| V2 | Take-off safety speed | The scheduled speed used to meet one-engine-inoperative climb requirements after lift-off. |
| VREF | Landing reference speed | The reference speed for the selected landing flap configuration and predicted landing weight. |
| VAPP | Approach target speed | Usually VREF plus the wind or minimum additive required by the operator's procedure. |
Normal 737-800 take-off figures commonly appear in the 130s, 140s or 150s KIAS, but that is only a reasonableness check. There is no universal set of 737-800 speeds to copy. Our broader guide to aviation V-speed terminology explains the regulatory terms and other speeds such as VMCG and VMCA.
How are Boeing 737-800 take-off V-speeds calculated?
Valid 737-800 take-off speeds come from certified manufacturer performance data implemented in approved tables or calculation software, not from one simple public formula.
- Establish the aircraft data. Enter take-off weight, centre of gravity where required, selected flap setting and the available engine thrust rating.
- Enter the runway and weather. The calculation needs the exact runway or intersection, available distance, slope, elevation or pressure data, temperature, wind and runway condition.
- Apply configuration penalties. Engine and wing anti-ice, air-conditioning bleeds, deferred defects and other operational restrictions can reduce available performance.
- Solve the runway limits. The system checks accelerate-stop distance, continued take-off distance, brake-energy limits and any wet or contaminated-runway requirements. V1 is selected within the permitted range.
- Check climb and control limits. VR and V2 must satisfy certified stall margins, minimum-control speeds, lift-off behaviour, obstacle clearance and one-engine-inoperative climb performance.
- Transfer and verify the speeds. Crews compare the performance result with the weight, runway, flap and thrust configuration entered in the flight management computer before accepting the speed bugs.
| Input change | Usual performance effect |
|---|---|
| Higher take-off weight | Generally raises VR and V2 and requires more runway and climb performance. |
| More take-off flap | Usually lowers lift-related speeds but increases drag, which can reduce climb margin. |
| Short, wet or contaminated runway | Can change the permitted V1 range, limit weight or make the planned take-off invalid. |
| Hot, high or tailwind conditions | Reduce performance margins and may require more thrust, a different flap setting or lower weight. |
| Reduced thrust or assumed temperature | Changes the available acceleration and climb performance; compatible speeds must be recalculated. |
Runway length does not simply make VR slower. If the aircraft cannot meet the runway and climb requirements, the proper solution is a different configuration, more thrust, less weight or another runway—not an invented lower rotation speed.
Why do two 737-800 calculations give different speeds?
Different results usually mean that an input or calculation method differs, especially the take-off weight, runway entry point, flap setting, thrust selection or runway condition.
V1 can also vary because it is partly a runway-performance optimisation rather than a pure aerodynamic speed. One valid solution may favour accelerate-stop margin, while another uses a different permitted balance between stopping and continuing. VR and V2 are tied more closely to weight, configuration and certified flight characteristics, although they can still change with the selected performance solution.
The 737 flight management computer may offer reference speeds after valid weight and flap data have been entered, but that does not necessarily constitute a complete runway analysis. The depth of calculation depends on the aircraft and operator installation. Final real-world figures must come from the operator-approved performance source.
How is Boeing 737-800 VREF calculated?
VREF is obtained from the certified landing-speed schedule using predicted landing gross weight and the selected landing flap, normally Flaps 30 or Flaps 40 for a normal 737-800 landing.
At the same weight, Flaps 40 generally produces a slightly lower VREF than Flaps 30, but flap selection also affects drag, landing distance, noise and go-around performance. Non-normal flap configurations require the appropriate checklist-derived speed adjustments rather than a normal VREF lookup.
VAPP is not the same as VREF. A common manual wind correction is half the steady headwind component plus the full gust increment, bounded by the operator's minimum and maximum additives. Procedures using autothrottle often command VREF plus 5 knots instead. The applicable aircraft and operator procedure always takes precedence.
How should simulator pilots calculate 737-800 V-speeds?
Simulator pilots should use the performance calculator supplied with the specific aircraft whenever it is available, because different aircraft models implement runway analysis and reference speeds at very different levels of detail.
- Load fuel and payload first. Confirm that the simulator, electronic flight bag and flight management computer show the same gross weight and units.
- Enter the exact departure data. Select the runway, intersection, flap setting, thrust option, weather and runway condition represented in the simulator.
- Calculate and transfer. Enter or accept V1, VR and V2, then confirm that the displayed speed bugs match the performance result.
- Recalculate after changes. A new runway, flap setting, payload, weather report or thrust selection invalidates the old figures.
For the stock FSX aircraft, our legacy calculator built for the default 737-800 demonstrates how V1, VR, V2 and VREF can be generated from simulator aircraft data. Its results are simulation aids and must not be transferred to another add-on or used for real-world flying.
- Blank FMC speeds: check that gross weight and take-off flap have been entered and that the aircraft has finished calculating its weight.
- Implausibly high or low speeds: look for a pounds-versus-kilograms error, unsynchronised payload data or the wrong flap selection.
- Speeds disappear after an edit: many systems delete calculated speeds when weight, flap, runway or thrust data changes; run the calculation again.
- No valid V1 result: the runway or configuration may be performance-limited. Do not substitute a generic chart value.
- Approach target is too fast: confirm that a wind additive has not been included twice by both the calculator and the pilot.