Ask The Pilot

[jb747]

Hi Pilots, in the following sentence, what does Left Base mean:
"An RPT, turboprop aircraft was on left base for RWY 34L at Sydney while independent visual approaches were in use."
Thanks

A circuit is the pattern an aircraft flies around a runway. It consists of multiple legs. Upwind, crosswind, downwind, base and finals. Upwind and finals are in the same direction, but at different ends of the runway.

So, base is the leg, at 90º off the runway heading, that’s just prior to the final leg.

Circuits can be flown in a clockwise (right) or anticlockwise (left) direction. Local rules normally decide what will be used.

Circuits and Landings | Flight Training Made Simple

Learning to land is the most challenging part of your flight training. This circuits and landings briefing explains exactly what you can expect in circuits, approach and landing.

www.ppl-flight-training.com

 

[straitman]

Thanks JB. I couldn't get my picture to attach correctly.

 

[AviatorInsight]

Hi Pilots, in the following sentence, what does Left Base mean:
"An RPT, turboprop aircraft was on left base for RWY 34L at Sydney while independent visual approaches were in use."
Thanks

Adding to what the others have said, the standard is for a left hand circuit. The idea behind this is that the runway is in sight of the pilot at all times. This is of course for smaller trainer type aircraft.

If given the option and I'm PF I'll opt for a right circuit just because I'll have the runway in view at all times (just like today into NTL). Places like AYE, MKY etc where it's compulsory left hand patterns, although not difficult, do require a bit more support from the captain, especially on base as to my profile because I won't necessarily have the runway in sight.

 

[AviatorInsight]

With the weather shaping up to be a wild day from the NSW south coast all the way up to Kempsey, I have no doubt that there will plenty of delays/cancellations. At this stage I have a 4 sector day tomorrow including the airports of NTL, BNE, SYD and OOL.

The underlined says that from 03 2000 UTC (6am local), wind is 200ºT 40 gusting to 55kts, visibility 7000m in Showers of Rain, Cloud Few 1000ft, Scattered 1500ft Broken 2000ft.

The TEMPO is Temporary periods up to 60mins in length between 6am and 1pm local time visibility dropping to 3000m in heavy showers of rain (noted by the +) with cloud Broken at 800ft.

 

[Aus ATC]

If given the option and I'm PF I'll opt for a right circuit just because I'll have the runway in view at all times (just like today into NTL). Places like AYE, MKY etc where it's compulsory left hand patterns, although not difficult, do require a bit more support from the captain, especially on base as to my profile because I won't necessarily have the runway in sight.

So in cases of a left circuit for arrival ( and this would likely be known some time out), would it be worth handing over the pilot flying duties to the LH seat? Asking that from the perspective of not fully appreciating the different roles on the flight deck - and an assumption that such a changeover could be managed reasonably promptly.

 

[AviatorInsight]

So in cases of a left circuit for arrival ( and this would likely be known some time out), would it be worth handing over the pilot flying duties to the LH seat? Asking that from the perspective of not fully appreciating the different roles on the flight deck - and an assumption that such a changeover could be managed reasonably promptly.

Yeah you could I guess. But I still use the autopilot until I’m on base and only until I have the runway in sight. This allows the Capt to then give me instructions, bit more/less rate of descent, etc. Once I’m happy with the path I’ll disengage both the autopilot and autothrottle and fly it like the Cessna, by that I mean I’m 90% looking outside and only just scanning the inside.

 

[jb747]

So in cases of a left circuit for arrival ( and this would likely be known some time out), would it be worth handing over the pilot flying duties to the LH seat? Asking that from the perspective of not fully appreciating the different roles on the flight deck - and an assumption that such a changeover could be managed reasonably promptly.

Whilst it is easier to do the circuit to the same side as the flying pilot, it isn't a problem to do it the other way. Mind you, visual circuits were not often on the A380 menu...but it was no harder in that aircraft than any other.

 

[flyer89]

I know you said you have no interest in flying anymore JB, but are you sure you don’t want to reconsider? Looks like a fairly cushy job.....

 

[jb747]

I know you said you have no interest in flying anymore JB, but are you sure you don’t want to reconsider? Looks like a fairly cushy job.....

Not so much a case of no interest, but having survived as long as I have, I see no reason to give aircraft any more chances, especially with that sort of flying.

And why has the FO got his hands on the controls?

 

[flychrisfly]

And why has the FO got his hands on the controls?

That was going to be my question!

 

[RooFlyer]

And why has the FO got his hands on the controls?

Given how nervous and fidgety the guy in the left hand seat looks, he probably thought it was a good idea!

 

[AviatorInsight]

As was my question! Also that is a very ancient autothrottle not to mention there was also probably a radio operator, a navigator, another pilot, a flight engineer, a ground engineer and an astronaut on board too.

 

[Quickstatus]

Slats, slots, notches, fences

Some fighter aircraft have a notch in the leading edge. Presumably this causes a vortex to form over the aero foil. How does this maintain the boundary layer and delay to separation at a high AoA?. Is this also how wing fences work?

Commercial aircraft don’t seem to have have notches or wing fences (except at the wing tips). Why is this?

 

[ChrisGibbs]

Was on Sundays 9 June QF1 SYD-SIN A380 service. Our boarding was delayed by about 30 minutes due to a failure of the hydraulics on one of the catering trucks. When we boarded the temperature inside the cabin was unusually high due to a failed APU. The Captain (Harry Wubben from QF32) explained that with help from the ground engineers they would start two engines using ground power at the gate prior to push back. Over the years a failed APU is not unusual and rarely gets a mention. The reason this one was different was that all the doors were closed and the aerobridges had been withdrawn however there was still and engineer onboard. From what I was told by the CSM, after starting the first 2 engines and prior to pushback, the engineer exited the aircraft to ground level via an avionics hatch. I'm not sure if I was being fed a line here but why would you need an engineer onboard during a ground power start and how often does someone use the avionics hatch to enter / exit the aircraft.

 

[jb747]

Was on Sundays 9 June QF1 SYD-SIN A380 service. Our boarding was delayed by about 30 minutes due to a failure of the hydraulics on one of the catering trucks. When we boarded the temperature inside the cabin was unusually high due to a failed APU. The Captain (Harry Wubben from QF32) explained that with help from the ground engineers they would start two engines using ground power at the gate prior to push back. Over the years a failed APU is not unusual and rarely gets a mention. The reason this one was different was that all the doors were closed and the aerobridges had been withdrawn however there was still and engineer onboard. From what I was told by the CSM, after starting the first 2 engines and prior to pushback, the engineer exited the aircraft to ground level via an avionics hatch. I'm not sure if I was being fed a line here but why would you need an engineer onboard during a ground power start and how often does someone use the avionics hatch to enter / exit the aircraft.

In some parts of the world, external conditioned air is readily available, in amounts sufficient to keep the cabin cool without running the APU. Australia isn't one of them. A large group of people put out a lot of heat. So, generally you want the boarding to happen as quickly as possible, so that you can get the doors shut, and then get an engine running for air. But, engines running for any lengthy time at the gate causes issues with OH&S, and various airport rules, so you mostly just need to push as soon as you do start. You can't push back without starting a couple of engines though, as you need electrics and hydraulics for the push and start.

You do not need an engineer to be on board for any of this. My guess would be that the engineer was involved in something else. But, the alternative to keeping him on and then letting him out via the electronics bay, would have involved not starting the engines and closing the doors...no a/c. In that case, possibly no boarding until he'd finished. So, a nice lateral solution.

As for how often the bay is used as access. Virtually never. I can recall doing it once on the 767, and never on anything else.

 

[Quickstatus]

Is it a regulatory requirement that engines can only be started when aircraft doors are shut?

 

[jb747]

Slats, slots, notches, fences

Some fighter aircraft have a notch in the leading edge. Presumably this causes a vortex to form over the aero foil. How does this maintain the boundary layer and delay to separation at a high AoA?. Is this also how wing fences work?

There's a fair bit of reading about this, and leading edge devices in general, in wikipedia.

Most of this stuff is a kludge, added after the aircraft is too far down the line to production (or already in service) to allow it to be fixed (i.e. designed out) properly.

Fences and notches are mostly involved in attempts to reduce 'spanwise' flow, i.e. the tendency of the air to flow along the wing, rather than over it. As the spanwise flow increases, it results in a situation in which it will stall earlier...which gives a couple of nasty outcomes. Firstly stalling towards the tip results in increased tendency towards 'wing dropping', rolling as it enters the stall. You actually want the stall to progress from the fuselage out to help with control, not the other way around. Secondly, on a swept wing, stalling at the tips moves the centre of pressure forward, resulting in a further tendency to pitch up, which in turn makes the stall deeper.

Commercial aircraft don’t seem to have have notches or wing fences (except at the wing tips). Why is this?

Have a look at some of the Russians. They've got fences galore.

 

[jb747]

Is it a regulatory requirement that engines can only be started when aircraft doors are shut?

Not that I know of . But many airports have local rules that limit running time at the gate.

There are a lot of reasons not too though. Safety of people on the ground, noise, both externally and internally. Risk of FOD.

 

[Quickstatus]

In swept wing tip stall, perhaps the pitch up tendency is also caused by the lack of lift at the tips where the wing tips are aft of the CoG, so the wingtips drops off causing a pitch up moment?

 

[jb747]

I think I said that...think centre of pressure.