Spin off from 421 sale thread. I suggested 5000' was a comfortable runway length for a not too hot, not too heavy 421 takeoff. My reasons are attached.

Breaking ground in a short distance is not the problem. It's the V1 cut. I understand this is a philosophical debate, but I for anywhere close to gross or above standard temp, a long runway is a nice thing to have.

My plane is somewhat porky (lot of rack mounted avionics) and does not have VG's. Best I can tell they bump MGW 129 lbs - but you can see how bad the single engine performance is at 7450 and how much it is changed from 7200. The 7579 max gross with VG's would be even worse.

Standard day at SL with 1,700lb payload says about 1,800'.

I think I flew my 421 at gross less than 10 times. Normally I was 800lbs under.

Max payload in the PBaron was 1640. 1750 in some...

Those charts are the reason fuel planning is very important (along with the OEI chart). Most everyone carries unnecessary fuel in their twin. I see that as unnecessary risk.

I bought the 421 partially because I did not like flying the PBaron at GW. If you are flying a 421 at gross regularly, you need a turbine IMO.

I agree - weight is a huge issue. And temp too - I see "standard" temps less than half the year. I rarely fly at gross, but 7000-7200 is common. 90F and 7200 lbs is not a crazy situation but the performance is very marginal.

The 421 is a great plane that can carry a load better than any other piston twin. But it's NOT a "if you can shut the door, it'll fly away on one engine" airplane. That's all I'm getting at.

I remember using that chart to help justify a friend to buy a turboprop..
(Which in reality probably doesn't do all that much better leaving Pagoso Springs, CO in summer).

But being able to say: might you'll get to 50' altitude before Durango was fun.

Charles I think your example with the eight people is numerically correct but I think in reality most folks don't fly 421s with eight adults in them as regular procedure.

That was my point. It's not common practice because it's not practical

I'm talking comfort, as in stretching out your legs, not runway length. With your inclusion of graphs I assumed you were talking performance.

Well it doesn't take 8 adults to get near 7450 lbs in a 421. Mine is 5200 empty, and 6556 with full fuel which isn't a particularly huge amount. (226 gallons - I burned 120 in a 3:15 HKS-SAT against awful headwinds two days ago.) 900 lbs of pax/bags isn't too hard to come up against even with 6 adults.

As for 8 adults ... I wouldn't take them HKS-ISM because of legroom, but I don't take them HKS-NEW for dinner because of W&B.

I had a Cessna 421B, and these opinions are based on that airplane. I now have a Baron B55 with IO550's. The 421 had a Robertson STOL kit.

I flew the 421 and the Baron into the same small strips, such as Healdsburg KHES (2650') and Palo Alto (KPAO) at 2450' or so as I recall. No issues in or out with either plane, though obviously margins are reduced.

I filled all 8 seats on the 421 exactly once, with teenage girls.

And of course as the field elevation got higher, the 421 is favored because of turbos, duh.

Don't know what an unmodified 421 would be like.

Hello Charles,

Thanks for the performance info.

I restarted the other thread because I see changing price dynamics in these cabin class twins.

The charts and inputs from others help with assessing these aircraft.

Thanks again.

After 10 years and 1,000+ hours with my 421C, I love long runways. My favorite Lindbergh quote: "The question is not how little runway an airplane needs, but how much it needs to operate safely."

3,000' is my absolute minimum, and requires day, VFR, dry, and light.

4,000' is my preferred minimum.

With night or weather, 5,000' or 6,000' is preferred.

As others have reported, the airplane is physically capable of using much shorter runways - as long as everything works.

If something goes wrong at a bad time, 10,000' can be tight.

Charles may recall my asking about going to Creve Couer (1H0) for the WxBrief class. Creve is 4500' with LPV approaches to each end, though with high minimums: 350-500' and 1.5-2 miles visibility. Although Creve was the most convenient airport, I went to SUS instead. I knew there was a good chance I would arrive after dark and 4500' is tight for an airport I have never been to before in the daytime. When I contemplated a reasonable chance at a missed approach and having my rental car at the wrong airport, the few additional miles to SUS looked very attractive.

It is hard for most people to understand that a 421 should have longer runways than many straight-wing jets.

421C can use short runways. I can land and TO in 2500 feet at SL Depending on weight and temperature and obstacles. The risk is reduced by the length of the runway.
A good skillful 421C pilot should be able to use anything from 2500 and longer with the required conditions. At night I prefer at least 4,000. Daytime 3,000 to 4,000.

Hello Gerald,



Very useful information.

Thanks.