Flaps 30 or Flaps 40 for a Boeing 737 landing?
For most Boeing 737 landings, Flaps 30 is the normal choice; Flaps 40 is used when approved performance data favours its lower VREF and shorter landing distance. Flaps 40 adds drag and needs more thrust. On a 737-700, the standard Flaps 40 limiting speed is 162 KIAS; verify the cockpit placard.
In our Aviation & Real-World Flying coverage, we treat Flaps 30 as the practical default and Flaps 40 as a performance choice. Both are normal landing configurations when permitted by the aircraft and operator procedures; neither is universally correct for every runway or weather condition.
Which Boeing 737 flap settings are used for landing?
Flaps 30 and Flaps 40 are the usual Boeing 737 landing-flap selections.
Most 737 flight decks provide flap-lever detents at UP, 1, 2, 5, 10, 15, 25, 30 and 40. Flaps 40 is the highest detent. Flaps 15 may be specified by certain non-normal procedures, but it is not the routine alternative to Flaps 30 or 40.
What changes between Flaps 30 and Flaps 40?
Flaps 40 produces more drag and a lower reference speed than Flaps 30 at the same landing weight.
| Factor | Flaps 30 | Flaps 40 |
|---|---|---|
| Typical use | Normal landing setting for many operators | Used when additional landing-performance margin is required |
| VREF at the same weight | Higher by a few knots | Lower by a few knots |
| Drag and thrust on final | Less drag and usually less thrust | More drag and usually more thrust |
| Calculated landing distance | Usually longer | Usually shorter |
| Initial go-around drag | Lower | Higher until the flaps are reconfigured |
| 737-700 flap limiting speed | 175 KIAS | 162 KIAS |
The VREF difference is normally only a few knots and changes with weight and variant. That modest reduction can still improve stopping margin, but only if the correct Flaps 40 speed is flown and the touchdown occurs in the intended touchdown zone.
What is the Flaps 40 limiting speed on the 737-700?
The standard Boeing 737-700 Flaps 40 limiting speed is 162 KIAS.
This limit is VFE: the maximum indicated airspeed with the flaps extended in that position. It is not VREF, a target approach speed or a groundspeed limit. Plan the deceleration so that Flaps 40 is selected below 162 KIAS rather than using the limit as a target.
For comparison, the standard 737-700 Flaps 30 limit is 175 KIAS. The cockpit flap-speed placard and documentation for the exact aeroplane always take priority, particularly with a different 737 generation, a modified aircraft or an add-on whose modelling does not exactly match the real 737-700.
Why is Flaps 30 the usual 737 landing flap?
Flaps 30 provides a useful balance of runway performance, final-approach thrust and go-around capability.
- Routine runway performance: it normally provides ample stopping margin on a suitable dry runway.
- Less drag: the engines need less thrust to maintain the approach path than they do with Flaps 40.
- Lower initial go-around drag: the aeroplane accelerates without first carrying as much landing-flap drag.
- Operational efficiency: lower thrust on final generally reduces fuel use and noise compared with selecting full flap for every landing.
A go-around from either configuration is a normal, approved manoeuvre. From Flaps 30 or 40, follow the aircraft's go-around flap schedule rather than moving the lever directly to UP; a typical 737 procedure initially commands Flaps 15 before later retraction on schedule.
When is Flaps 40 the better choice?
Flaps 40 is the better choice when its calculated landing-distance benefit is needed and the applicable procedures permit it.
- Short or performance-limited runway: the lower VREF can reduce the required landing distance.
- Reduced stopping margin: runway slope, elevation, landing weight, wind and temperature can make Flaps 40 advantageous.
- Wet or contaminated surface: use it when the approved landing data shows a worthwhile benefit, not merely because rain is present.
- Restricted runway exit: Flaps 40 may help where the planned exit requires earlier deceleration, provided the landing calculation remains the controlling factor.
Higher landing weight or poor weather does not automatically require Flaps 40. Use the add-on's EFB, FMC or performance documentation where available, and ensure its assumptions match the runway condition, braking setting and wind.
Do strong crosswinds or gusts mean you should use Flaps 40?
No. Many procedures prefer Flaps 30 in strong or gusty crosswinds, while a tight runway-performance calculation may still favour Flaps 40.
Use the reported wind rather than guessing from the windsock. Our guide to extracting wind and weather from a METAR explains the relevant report groups, while our crosswind landing technique guide covers alignment, gust handling and control inputs.
A METAR does not necessarily provide complete runway braking information. Check any separate runway-condition report supplied by the simulator, aircraft or scenario, and apply the operator's wind-additive method rather than inventing one.
How should simmers choose between Flaps 30 and Flaps 40?
Choose the landing flap from the aircraft procedure and landing-performance data before configuring for final approach.
If the 737 is consistently high and fast before the final flap selection, correct the descent plan rather than relying on Flaps 40 as an airbrake. Our 737 descent and approach set-up workflow covers the earlier energy-management steps.
- Check the applicable procedure. The exact 737 variant, airline profile or add-on may specify Flaps 30 as standard and reserve Flaps 40 for performance-limited landings.
- Confirm landing weight and runway data. Consider usable length, slope, elevation, surface condition, temperature, wind and expected braking.
- Compare the available landing calculations. Select Flaps 40 only when its lower speed and shorter calculated distance provide a useful margin.
- Select the matching VREF. Do not retain the Flaps 30 speed after deciding to land with Flaps 40.
- Respect each flap placard speed. Decelerate through the approach while extending the flaps in sequence; do not select Flaps 40 above its limit.
- Stabilise before the prescribed gate. The landing flap, gear, speed, thrust and checklist should be settled. Go around if large corrections are still required close to the runway.
For a more detailed study-level NG flow, our PMDG 737NG operations and landing tutorial covers airline-style configuration and approach management.
What speed should you fly with Flaps 30 or Flaps 40?
Fly the VREF calculated for the selected flap setting and actual landing weight, plus the wind correction required by the applicable procedure.
A correctly modelled 737 FMC normally provides landing reference speeds on its approach-reference page. Select the entry for the intended flap setting, verify that the gross weight is sensible, and set the resulting target as required by the add-on. Some simulations label the final target, including its wind correction, as VAPP.
There is no universal Flaps 30 or Flaps 40 approach speed. Copying a speed from another flight can leave the aircraft too slow at a higher weight or unnecessarily fast at a lower one. A gust additive also increases touchdown energy and can consume some of the landing-distance gain expected from Flaps 40.
Common Flaps 30 and Flaps 40 mistakes in simulators
Most simulated 737 flap problems come from confusing a speed limit with a target speed or making the configuration change too late.
Treating 162 KIAS as the Flaps 40 landing speed
The 162 KIAS figure is the 737-700 flap limiting speed, not the speed to fly over the threshold. Use the calculated Flaps 40 VREF for the aircraft's landing weight.
Selecting Flaps 40 too late
Late selection causes a rapid drag increase, deceleration and a fresh thrust adjustment when the approach should already be settled. Choose the landing flap early enough to stabilise speed, pitch and power before short final.
Flying Flaps 40 at the Flaps 30 target
Keeping the higher Flaps 30 speed can produce a longer float and discard much of the expected landing-distance benefit. Recheck the selected FMC reference, speed bug and actual flap-lever position.
Using full flap to rescue a high or fast approach
Flaps 40 is not a substitute for correct descent planning. If the aeroplane remains high, fast or outside the stabilised-approach criteria, go around rather than forcing the landing.
Getting an unexpected flap-overspeed warning
Check indicated airspeed rather than groundspeed or true airspeed, then inspect the actual cockpit flap position. If the lever moves without a command, look for duplicate flap bindings, an incorrectly calibrated hardware axis or a control spike that briefly selects a higher detent.