Min Clean Speeds
 

Hi All,
Am a controller but hopefully not treading on too many toes posting in this forum, with a question about the above.
As I work approach radar frequently assign aircraft lower speeds, and then theres occasionally a series of 'bartering' over what they would like to do vs what i want them to do, so they can stay clean.
Ive been told the MCS for the RJ1H (BAe146-Rj100) is 190kts, i was wondering if anyone could generally put MCS' to the following..
Dornier328
ATR42-500
DHC8-300
DHC8-Q400
BAe146-200
Bae146-RJ85
Saab340
Saab2000
Fokker50
Thanks
Al
Thames radar

rotorblades The min clean speed in most aircraft is a variable depending primarily on weight, thus a lightweight 146 can fly slower than a heavy RJ100.
Your question suggests that you are making an assumption in order to help the aircrew; a good idea, but what is the objective?
If ATC require a slower speed then they should request it; if the aircraft cannot manage that speed clean, then flap etc can be selected, or if the crew are unable to comply they should inform ATC.
Similarly if the crew require a specific speed they can make the request; there are several communication possibilities – “request speed xxx if able” – “request speed xxx due to weather” – “Emergency, I will maintain speed xxx”. ATC normally do their best to help requests and have an exemplary record in emergencies. All that is required is clear and concise communication.
Perhaps those crews who wish to keep the aircraft clean are unfairly imposing on ATC’s flexibility; if ATC give too much then workload and safety may suffer, what price a near miss, and whose fault is it.
Why should crews need to stay clean? It might save some fuel, but at the expense of increased workload or risk; it would only take one nasty incident just below min clean speed to upset the fuel economics argument. Higher speeds reduce the time available for assessment and planning for both the crew and ATC; turn radius is higher, etc. Perhaps time is the issue, but the same applies, just consider the number of accidents and incidents that involved an attempt to save time; time is not money especially if you have an expensive accident.
Thanks for your consideration, but I would prefer a smooth flowing and safe traffic pattern rather than ATC attempting to prejudge the aircraft weight, min clean speed, etc. ‘You can’t keep all of the people happy all of the time.’
P.S. if it is Thames Radar into LCY then 146/RJ crews need to dirty up and reduce speed earlier than normal for their steep approach procedure.

safetypee

Thanks for that - but could you answer the question! We all know we can specify a speed, or the crew can ask for a specific speed, but as most approach units only use 250+/220/190 or 180 as MCS/160 kts then that is the question.

Whilst not an ATPL we are all aware that there is a 5.5 deg GP and that planes need to stop to get the passengers off.

Ball park figures would be nice.

Hi Safetypee,
We like to keep our aircrews happy At London City, because they help US out when we are busy or have made a merry stew out of the traffic pattern with little whinging, and 10 kts difference between 180 & 190 is not enough to get worried about. So it generally is appreciated by pilots to let them stay clean longer, especially as we reduce speeds a lot earlier than other units. eg Heathrow reduce spped of a/c to 180 on the base leg turn about 20-23 miles ish. We when busy can reduce our aircraft to 180 35-40 miles out, due to lack of holding facility - but thats another thing altogether.
Im not talking about telling a pilot to fly '160 to 6 miles' and the pilot requesting 220kts, that is a different thing altogether, im talking 10-15 knots either side. Ill regularly reduce the RJs to 190 and the Fokkers to 180 because that 10 knots doesnt make much difference to the vestoring or safety of the traffic flow. If it was a problem then i wouldnt try and keep one clean they'd all be 180 or 190 or whatever. Though I do appreciate where you are coming from in your post
Alex

Thanks Alex; it a long time since I visited LCY, but I did attend on 24 July 1988 !
Perhaps the issue from the crew’s perspective is because a steep approach requires a shorter final distance, and perhaps higher than for ‘shallow’ operations, they expect to remain at a higher speed at a location where ATC procedures for a shallow approach might require a speed reduction.
[b]AlanM[b/] ‘Clear and concise communications’ – we now have the question and information about ATC standard speeds.
In my day the 146/RJ min manoeuvring speed (clean) was Vfto+10 if that helps! However, 180/190 kts should suit most occasions.
The 5.5 deg approach ‘awareness’ should include the 146/RJ crew’s need to be fully configured for landing and at the approach speed as the final descent is commenced, i.e. no deceleration on final approach.

Most of the aircraft if 'left alone' with regards to speed, slow down to about 160 at 10DME, except VLM with their Fokkers that can do 224kts until 7DME then feather the props & snap the necks of the poor pax in the back as they pull about 6negG's!
The fastest ive seen is a Shell Falcon with a Ground speed of 380 with 12 miles to go. The highest approach was an EAE Atr42 drop from 3000' at 4 miles with overcast cloud at 800' - and according to the tower popped out of the cloud in significantly nose down profile but flared and made the best landing that controller had ever seen!
Oh for a camera!
Alex

OK, FK50 for my company, minimum clean 130 (but then bank limited to 15 degrees), so we use 140kts. However, I generally appreciate they way you handle us at LCY. At many airports, we are asked to slow to minimum approach speed, which we do. The guy following then thinks we have selected reverse gear as we slow up to 110 or less. It appears that at LCY, it is known that we will go that slow. The bit I'm not so keen on it being vectored all over Kent at 220 kts for delaying purposes when I'd prefer 160 (reasonable compromise between rough air, holding, ice, handling etc.) which I do ask for and normally get).

And, for me, given free speed for Rwy 28, 19 tons and no tailwind I'd stay at 220 until 8.5 nm, then slow up. The G/S will then be intercepted just below 170kts. For Rwy 10, I'm a lot more conservative and will fully establish with Gear Down, Flaps 25 and speed <150 or so. And with the FK50, flaps 10 is no real hinderance. There is no appreciable increase in drag but a reasonable increase in lift.

Hope this helps.

Hi,
Thanks for your comments they are very interesting, and i'll take into consideration vectoring around kent.
The only reason we sometimes opt to keep inbounds faster rather than bringing the speed right back to 160 is the knock on effect it has on the aircraft following as they all have to slow down substantially and eventually a wave effect takes its course and either some have to go into a holding pattern over spear, or inbounds get sped at 180 before crossing the english coast.
Thanks & speak soon no doubt
Alex