An unplanned hold: entry, wind correction, and a fuel clock
You are in a Cessna 172S at 6,000 ft, 12 NM east of the OTTER VOR, heading 270, cleared direct OTTER. The fuel totalizer shows 24 gal, the engine burns 9.5 gph at this power setting, and the airplane trues out at 110 kt. Your alternate is 30 minutes away, and your personal minimum is a 45-minute reserve. ATC issues: 'N123AB, cleared to the OTTER VOR, hold north of the OTTER VOR on the 360 radial, right turns, maintain 6,000, expect further clearance at 2135Z.' It is 2105Z. The wind at 6,000 ft is 360 at 30 kt. Your panel has a single VOR/HSI and a GPS. The airplane is not equipped with a fuel totalizer alarm, and you have no weather radar, so you are relying on the destination forecast you received on the ground.
1. Describe the entry you will make and the first turn after crossing the fix, and explain why.
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Holding north of the VOR on the 360 radial means the inbound course is 180. With right turns, the holding pattern lies to the right of the inbound course, which is the west side. You are approaching from the east, the non-holding side, so this is a direct entry. Cross OTTER, turn right to the outbound heading of 360, fly the outbound leg on the radial, then turn right to roll out on the 180 inbound course and correct for drift. Two details matter here. First, because the wind is aligned with the legs, the outbound heading and the radial will nearly coincide; the real work is timing and the drift you pick up in the turns, which will push you east of the outbound course. Second, the direct entry is a consequence of the geometry, not a name to memorize: if you had been approaching from the holding side, well away from the outbound course, the entry would have been a parallel or teardrop instead, and the turn after the fix would be different.
2. How long will you fly the outbound leg, and how do you correct for the wind?
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The goal is a 1-minute inbound leg, with legs at 6,000 ft timed at 1 minute when there is no wind. Outbound on 360 with the wind 360 at 30 kt, your ground speed is 80 kt; inbound it is 140 kt. One minute inbound at 140 kt covers about 2.33 NM, so the outbound leg has to cover the same distance at 80 kt, which takes about 1.75 minutes, or roughly 1 minute 45 seconds. Fly that outbound time rather than a flat minute, then time the inbound leg and adjust: if the inbound leg runs long, shorten the outbound; if it runs short, extend it. Because the wind is a pure headwind and tailwind, little heading correction is needed on the legs themselves, but the turns will drift you east of the outbound course, so expect to correct back onto the radial as you complete the turn inbound. At 6,000 ft the timing adjustment is small but persistent, and it compounds over several turns if you ignore it.
3. When must you leave the hold, and what will you tell ATC?
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Start with the fuel you can actually spend holding. You have 24 gal aboard. The 45-minute reserve at 9.5 gph is about 7.1 gal, and the 30-minute alternate is about 4.75 gal, so 11.9 gal is committed and 12.1 gal is available for holding. At 9.5 gph that is about 1.27 hours, or 76 minutes. The hold begins about 2110Z, so you must be out of the hold and on your way to the alternate by roughly 2225Z at the latest. That is not a comfortable number relative to the 2135Z expect-further-clearance time, because a 30-minute hold consumes only about 4.75 gal and still leaves you near the limit if the destination weather is worse than forecast. If no further clearance arrives by 2135Z, ask for it. By 2200Z, tell ATC plainly that you must depart the hold by 2225Z for fuel, and request either an onward clearance or a diversion. Do not wait until the reserve is in play before saying anything.