turboplanner Posted August 20, 2017 Posted August 20, 2017 Disclaimer · Don’t try this by yourself; it takes an instructor to teach it in real time, and several hours to come up to speed. · Disregard what the other pilots might do to react to my speed and track. · We’ll disregard RPT aircraft · Aircraft positions at the start are fictitious. · All flying has to be within the POH. · Circuit will be left hand. · There will be twelve aircraft in the circuit, but for this exercise we’ll take out 7 of them. TAKE OFF AND IMPACT ON CIRCUIT PATTERN The Baron, climbing at 1700 fpm will reach his 500’ crosswind turn before the end of the strip, compounded by also being the fastest to reach 1000’ circuit height, so theoretically could make the tightest circuits, but tend to ease out to give the pilot more time to manage the aircraft. The Drifter, climbing at 900 fpm should also reach his 250’ crosswind point well before the end of the strip and 500’ circuit height right in beside the airstrip. Although he has the shortest cruise speed, he has the shortest circuit legs, so in terms of time is not as different as the speeds might suggest. The Warrior, Cessna 152, Jabiru, Cessna 172 all have about the same climb rate, so should be flying roughly the same leg lengths, starting with a crosswind leg well beyond the end of the runway. For this exercise, we’ll have the Cessna 152 two up, so its performance is hopeless, and it will take longer to climb to 500’ for crosswind, and longer to turn downwind at 1000’ so it will be a long way out flying downwind. LANDING IN HEAVY TRAFFIC I like to approach on the dead side of the runway and enter the circuit downwind. You get a side on view of the traffic, so some idea of the speeds, the distance to each end of the circuit is about the same, so you get a better view of aircraft at both ends, and in a very busy circuit, the circuit will almost be dotted in by aircraft. You also have a good visual for letting down from 1500’ to 1000’. However, the biggest advantage is that you have a big wide envelope to choose where you are going to slot into the pattern. I see a Baron turning downwind, so while I normally would have plenty of time to slot in without worrying who is behind me, I leave some throttle on during the descent, and pick the speed up to 115 kts. Getting into the circuit without delay, slotting in at the last available location – midfield, and letting momentum power me on the downwind leg for a while. What I’ve done is given the Baron a good buffer. He’s probably coming after me at 120 kts at this point, but he’s not going to run over the top of me, or have to suddenly pull the throttle back and use flaps. If I see he is getting balked when I turn Base, I’ll probably turn final a little early and come down at a slight angle. I finally spot the 152 way out wide. He’s ahead of me now, but when he turns, it’s going to take him a minute or so just to get in to my downwind track, so I just put him to the side for now, and continue on at cruise speed, having washed off my earlier descent speed. On the way in I saw the Jabiru about three quarters of the way down the strip. He now makes an early base turn, leaving me exposed to a go round when we get to final, so I pull on 1 stage of flap, pull the throttle back for level flight and trim the aircraft. I know the Baron will be doing the same behind me, because we both heard the Jab’s Base call. When inbound I also saw the Drifter climbing out and it is down below on its own downwind leg, closer in to the strip. Looking at his progress, I estimate that the Jab is going to get in over him, but he might block me, so I increase speed. The Cessna 152 is still way out on downwind, and I can see the Jab on final so I’m watching and waiting for the Cessna, and as soon as I see the wings start to move I call Base and turn, so I now have the slot behind the Jab. The Baron calls a couple of seconds later right behind me. The Jab’s landing, I’ve already increased speed on the base leg, and come down slightly faster than normal, knowing the Baron’s crowding me to beat the C152, but he’s still out there somewhere and no longer in the mix. The Drifter is, however, and since aircraft at greater height must give way to aircraft at lower height, I can’t afford to meet him at his intersection on final. The Drifter’s descent speed has slowed his forward progress, and I get down final ahead of his turn and so does the Baron. Many pilots in the Baron’s shoes at this point would opt to go round, but he’s a daily flyer, and will hang on until the last minute. I touch down on the piano keys in maximum ground effect, get on the brakes, and quickly make the first turn off the strip. The second I’m over the white line I call clear runway, I look out the window and see the Baron start to sink for a landing. Any hesitation on my part and he just would have gone round. Now add in the other 7 aircraft with commonly three or four hanging there on final hoping someone else will lose their nerve and go round, and you can see there are quite a lot of decision points, and speed track adjustments required if you want to avoid go rounds.
facthunter Posted August 21, 2017 Posted August 21, 2017 ATC people at primary airports have to have a good working knowledge of the speeds various types use in the circuit. So does anyone operating at places like Moorabbin. This is expecting a bit too much of many. Also on a day when there's a reasonably strong wind down the runway, the groundspeed of slow planes is reduced % wise by a lot more than with faster types so a long final in those circumstances has the potential to hold up others.. .Perhaps a meeting of all operators /schools on the airport to discuss circuit size minimalisation benefits. Of course a small circuit means the same chores must be done in a lesser time. If you are trying to reduce speed in some types (Coming in a bit hot) it requires extra time but most of that should have been done before you enter the circuit. Most extended circuits you are just boring along burning fuel at constant speed and height , no frequency change, a few checks easily coped with if you are organised. Traffic is the problem. the same number must land regardless of the circuit size, unless some go around. Nev 1
M61A1 Posted August 21, 2017 Posted August 21, 2017 All well and good, but the issue here is not having to fit in with faster or slower aircraft, as the larger circuit flown by a faster aircraft generally takes the same amount of time. The issue is other aircraft with similar approach speeds flying unnecessarily massive circuits and forcing you to extend downwind unnecessarily and at times unsafely.. 2
SDQDI Posted August 21, 2017 Posted August 21, 2017 I think Turbs was basically agreeing that cutting in was ok M6:thumb up:. In his example he had the 152 doing big circuits and he cut inside so I think he is basically agreeing that it is all good, as long as we don't blabber on on the radio which I totally agree with at any busy airstrip. 1
facthunter Posted August 21, 2017 Posted August 21, 2017 The older 150's are worse than a 152, but if you plane especially on a hot day isn't climbing too well commence the downwind turn below 1,000 feet to stop from being too far out, and keep the circuit more or less normal in planform. Achieve the 1,000 feet downwind about 1/5th of the way down wind. You can also creep in a bit on downwind if you are obviously further away than you like. Also higher performance planes taking off "light" can reduce their climb angle by increasing climb speed so as not to climb through the height ( on departure) people over flying and joining mid downwind might be at. There is a lot of variables but a bit of applied commonsense helps. The hairiest place is mid base for conflicting traffic, but you want to be right on it at base turn particularly, as far as knowing where everyone is. Nev 2
turboplanner Posted August 21, 2017 Posted August 21, 2017 I think Turbs was basically agreeing that cutting in was ok M6:thumb up:.In his example he had the 152 doing big circuits and he cut inside so I think he is basically agreeing that it is all good, as long as we don't blabber on on the radio which I totally agree with at any busy airstrip. The overtaking interpretation - inside 70 degrees - is in CAR 160, and other rules are in CAR 162. In the example I gave with the Cessna 152 being way out wide, I would have been well outside the 70 degrees, so was not overtaking, and because I got the wings up and called Base first, that then became the order for final; pretty much the same as if I'd joined the circuit ahead of the C152. It's not cutting in; I'm still allowing the C152 an uninterrupted circuit to Final and a successful landing, and you'll notice that the actions The Jab took, I took and the Baron took, all allowed the Drifter to complete an uninterrupted circuit. Cutting in implies that you jump in front of someone, who then has to slow down enough to allow you to clear the runway, or go round, and that behaviour will be jumped on. Radio is critical in high traffic circuits and two second transmissions are ideal, allowing the maximum number of people to get their calls in. When that happens, a scenario like the five aircraft I described used to have two references of where everyone was, but when the see and be seen policy was introduced, radio procedures started to slacken off, and it would be very hard to get direction with an additional 7 in the circuit, so yes, the blabbering needs to stop. What M61A1 said in #14 was: "Sooooo.....I hang the Drifter on the prop, somewhere around 35 kts if I try, where does that put the poor bugger in the Jab behind me?" That would indicate his biggest problem has been flying in the Medium Performance (1000') Circuit instead of his own Low Performance (500') Circuit, or perhaps the Jabs at that location are doing 500' circuits, so his problem is easily solved. My point is, if someone flies a circuit half way to the next town, you ignore them and fly your circuit, based on your aircraft Performance and specifications, by enlarging their circuit they get a distance which is exponentially longer, so inevitably they are going to fall behind one or several aircraft flying correct circuits.
kaz3g Posted August 22, 2017 Posted August 22, 2017 I agree with Nev's view. Whilst circuits should not be XCountry flying fitting in with other traffic is also important. Some views that from downwind to touch down should be within gliding distance is at best questionable given that one may have just flown 2/3/4 hours XCountry then all of a sudden the last five minutes you have to be in gliding distance of an airfield - test flying after maintenance excepted. i generally fly my cross-country trips at more than 1000' AGL...its circuits over built up areas that keep me close. Kaz 1 1
Graham Pukallus Posted August 28, 2017 Posted August 28, 2017 Thought this might be a good resource of information pertaining to this subject. Don't Make These 12 Mistakes In The Traffic Pattern 3
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now