Shamal Dust Arrival into OKBK: Minima, Fuel and Windshear
You are commander of a Boeing 737-800 arriving at Kuwait International (OKBK) at 18:20 UTC. The METAR reads: 33022G35KT 1200 R33L/0900U BLDU FEW010 41/12 Q1003. The TAF contains TEMPO 34028G45KT 0800 DS BKN008. ILS runway 33L is serviceable with HIRL and ALS. You hold CAT I privileges only, and the operator's CAT I minimum is RVR 550 m. Fuel remaining at the holding fix is 4,700 kg. Company figures: one approach and missed approach 400 kg, diversion to the alternate 35 nm away 600 kg, final reserve 1,100 kg. The alternate's TAF is similar with visibility 1,500 m in blowing dust. The first officer is pilot flying; both pilots are on their fourth sector with 11 hours on duty.
1. Assess whether the approach may be flown, and identify what the reported figures do and do not tell you.
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The approach is legal; the reported numbers flatter the situation.
- Minima. The controlling figure for the approach is RVR, not meteorological visibility. RVR 33L is 900 m against a CAT I minimum of 550 m, and the trend is U (improving), so the approach is authorised.
- But the 1,200 m visibility is a horizontal meteorological visibility in blowing dust, measured at one point. Dust is not uniform; the touchdown-zone RVR can be much lower than the mid-point or the reported visibility, and the visual segment after DH may be filled with dust that the transmissometer does not see.
- Wind. 330/22G35 gives a gust spread of 13 kt on a runway roughly into wind - that is a windshear signature, and the TEMPO group adds 45 kt gusts with duststorm and 800 ft cloud. Brief a firm go-around trigger: any windshear warning, any significant airspeed/glideslope deviation, or no visual reference at DH.
- Technique. Fly the approach with a gust correction (about half the gust, up to 20 kt) added to VAPP, keep autopilot until the visual segment, and be prepared to land firmly rather than to float in a shifting wind.
- Crew state. Fourth sector, 11 hours on duty, arrival into a dust-hazy airport at nightfall - this is the sector where monitoring fails. Brief who does what on the go-around before starting the approach.
2. Using the fuel figures, decide how many approaches are available and set a bingo point.
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Compute the committed fuel, then the spendable fuel.
- Committed: final reserve 1,100 kg + diversion 600 kg = 1,700 kg.
- Fuel at the holding fix 4,700 kg − 1,700 kg = 3,000 kg spendable on approaches and holding.
- One approach and missed approach costs 400 kg; add about 300 kg for 15 minutes of holding or vectoring. After one attempt: 4,700 − 700 = 4,000 kg, still 2,300 kg above the committed figure.
- A second attempt costs another ~700 kg, leaving 3,300 kg - still above the diversion requirement, but now the margin is thin.
Bingo: 1,700 kg (committed) + 400 kg (one more approach) = 2,100 kg. Reaching 2,100 kg means divert now, without discussion.
Two cautions. The alternate is 35 nm away with similar dust, so the diversion is not a guaranteed escape - if the alternate is also below minima you are into a genuine fuel emergency, which argues for one attempt, not three. And the decision must be taken at the bingo figure, not at the last moment when the fuel is already committed to another approach.
3. On short final at 300 ft you get a windshear warning and the airspeed drops 15 kt. Describe the escape and the follow-up.
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Treat it as a genuine windshear encounter, not a gust.
- Escape immediately: TOGA thrust, disconnect the autopilot and autothrottle, pitch to the flight-director windshear guidance (or the manufacturer's pitch attitude), and do not change configuration - gear and flaps stay where they are until clear of the shear and climbing positively.
- Do not chase the glideslope and do not retrim aggressively; the priority is attitude and terrain clearance, and the aircraft will be well below the normal flight path while the shear persists.
- Report it. "Windshear, go-around, runway 33L" - the controller must warn the following aircraft, and a windshear report protects everyone behind you. Note the altitude, the airspeed loss/gain and the position for the report.
- After the go-around: dust ingestion matters. Heavy blowing dust degrades compressor performance and can foul the engine; expect higher EGT and reduced margin, and if the engines behave abnormally, treat the diversion as mandatory rather than optional.
- Then reset. Back at the holding fix the fuel has just dropped by roughly 400–500 kg. Re-run the bingo calculation before deciding on a second approach - this is exactly the situation in which fuel decisions are made badly.