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To High For Touchdown. Now What?  
User currently offlineGunFighter 6 From Netherlands, joined Jan 2001, 404 posts, RR: 0
Posted (11 years 4 months 1 week 3 days 21 hours ago) and read 2361 times:

At what point does the pilot decide to abort the landing.

The plane is on its final approach. The pilot can already see the runway clearly.
He then notices that he is to high on the glideslope. He tries to correct this but when almost reaching the treshhold he is still to high. He knows he is gonna touchdown after the desired touchdown point.
Lets say its an B737.

Is it normal in this example that the pilot proceeds with the landing? He just needs to brake harder. Or will the landing be aborted?
Also what do all you pilots use as reference when to high on the approach. At what point do you decide to abort?

Thanks in advance.
Cheers
G.


10 replies: All unread, jump to last
 
User currently offlineSaab2000 From Switzerland, joined Jun 2001, 1610 posts, RR: 11
Reply 1, posted (11 years 4 months 1 week 3 days 20 hours ago) and read 2329 times:

The question is why is the pilot too high on the glide slope? Glide slope deviations should be corrected early. The safe answer is that a go-around should be flown. But it depends on a number of factors. How long is the runway? Is there a tailwind component? Where do you plan to turn off?

The answer is that a go-around should be initiated as soon as one or both of the pilots determine the a safe landing might no longer be possible. Remember that the glide slope "cone" gets smaller as you approach the runway and a slight deviation over the threshhold is only a few feet. Nevertheless, a real pro will try to fly the glideslope right into the flare.



smrtrthnu
User currently offlinePositive rate From Australia, joined Sep 2001, 2143 posts, RR: 1
Reply 2, posted (11 years 4 months 1 week 3 days 20 hours ago) and read 2299 times:

I think in such a situation the pilots would decide to Go-around! There is a point in the approach where the airplane must be stabilised on final approach otherwise they will go-around- i think it's a specific height such as 1,000ft or something when a decision is made. If you were high on the glideslope you would know about it long before landing. There was an accident in the 1970's involving a PanAm 707 ladning at Pago Pago where the aircraft was above the glideslope and the captain tried to correct ending up significantly below the glideslope and slamming into a hill.

User currently offlineBackfire From Germany, joined Oct 2006, 0 posts, RR: 0
Reply 3, posted (11 years 4 months 1 week 3 days 19 hours ago) and read 2268 times:

Small corrections early = safe landing

Big corrections late = bent aeroplane

If your approach isn't stabilised, then you go around and try again.


User currently offlinePolair From United States of America, joined May 2001, 893 posts, RR: 2
Reply 4, posted (11 years 4 months 1 week 3 days 19 hours ago) and read 2253 times:

I think its like 150ft AGL...

User currently offlineGunFighter 6 From Netherlands, joined Jan 2001, 404 posts, RR: 0
Reply 5, posted (11 years 4 months 1 week 3 days 19 hours ago) and read 2251 times:

Hi,

I completely understeand Big grin
But isn’t It still possible to have a stabilized approach when you are a bit high ?
Or don’t you call it a stabilized approach in that case.

 Smile just curious.
But thanks for replies so far, me a lot clear.

Cheers.


User currently offlineLapper From United Kingdom, joined Mar 2002, 1562 posts, RR: 7
Reply 6, posted (11 years 4 months 1 week 3 days 19 hours ago) and read 2225 times:

He then notices that he is to high on the glideslope.

Shouldn't one of the pilots be constantly referring to the glideslope in order to avoid this and correct it early on?


User currently offlineGunFighter 6 From Netherlands, joined Jan 2001, 404 posts, RR: 0
Reply 7, posted (11 years 4 months 1 week 3 days 19 hours ago) and read 2219 times:

I am beginning to understeand that its not possible to be to high  Big thumbs up

oke other example.
pilots normally aim for the big markers on the runway as the desired touchdown point.
I have been on several flight where we flew way past this point.

how can this be described ?? is this the final flare which takes longer then normal??

Gerbert.


User currently offlineRJ From United States of America, joined Mar 2001, 198 posts, RR: 1
Reply 8, posted (11 years 4 months 1 week 3 days 14 hours ago) and read 2131 times:


Ok,

There are a few scenario's we need to look at. The fact is, you may not always have a localizer or glide slope to use for guidance. So we need to break this down by the different types of approaches one might get.

1. Approach with an ILS:

Our company states that if you are in IMC conditions, then you must have your approach stabilized by 1000' AGL. This means that the aircraft must be in the landing configuration, is at the proper approach speed (-0, +5kts) with the engines spooled up, and is on the proper flight path with a descent rate not exceeding 1000 fpm. If the approach is to be conducted in VMC conditions, then you must meet the same criteria as above by the time you reach 500' AGL.

2. Non Precision Approach:

The same criteria as above must be met. Therefore, the 1000 fpm descent rate will dictate whether or not you will be able to land safely. If you pick up the runway too late, that descent rate may not allow you to land in the touchdown zone. Therefore a missed approach will be executed.

3. Visual Approach with no guidance.

Yes, they can happen. I have flown many approaches without any guidance at all. Not even a PAPI or VASI. In this case a few rules of thumb can help you establish yourself in the proper position for a stabilized approach. You can plan to reach 1,500' AGL approximately 5 miles from the runway. At that 5 mile point, configure for landing and start a descent rate of approximately 700 fpm. A good rule of thumb on descent rates on visual approaches with no guidance is that your descent rate should never be greater than your altitude off of the ground. So if you are 2000' AGL, your descent rate should not be greater than 2000 fpm. If you are 1000' AGL, then your descent rate should not be greater than 1000 fpm. I think you get the idea. This will allow you time to arrest your descent and stabilize yourself before you land.

Have said all of this, it is important to remember that you must land in the touchdown zone. If you cannot land in the touchdown zone for any reason, then a missed approach/ go around must be initiated. And that is the key to the question asked in this post. If for any reason you are not stabilzed by the company's criteria or you cannot land in the touchdown zone, then a missed/go around will be conducted.

Happy flying!!!!

RJ


User currently offlineAlaskaairlines From United States of America, joined Jan 2002, 2054 posts, RR: 16
Reply 9, posted (11 years 4 months 1 week 3 days 5 hours ago) and read 1946 times:

I think it matters where you are at, in ANC I see lots of 737's landing half way down the rwy, buts thats done purposly, to conserve time.

-Dmitry


User currently offlineTT737FO From United States of America, joined Jun 2001, 472 posts, RR: 9
Reply 10, posted (11 years 4 months 1 week 3 days 3 hours ago) and read 1899 times:

>>>"i think it's a specific height such as 1,000ft or something when a decision is made.

RJ did a pretty good job explaining what his company Pilot Operating Manual allows. Usually company POMs will delineate their own procedures--which are in compliance (only stricter) with published procedures. It is important to understand Missed Approach Point, Minimum Descent Altitude, and Decision Height. Each varies according to avionics/flight instruments (POMs will also determine what a high mins Capt can/cannot do), airports, and navaids available...I'll add my 2 centavos.

1. A pilot making an instrument approach (Precision or Non-Precision) will have either a JEPP or IAP chart which will explain the altitudes, flight paths, and weather minimums for the runway at a given airport. A pilot adhering to the published procedures and/or vectors/altitudes assigned by ATC will be assured of terrain clearance and runway alignment.
Approach plates will have:
(a). A visual depiction called the plan view along with appropriate frequencies.
(b). A profile view which depicts minimum altitudes, maximum distance for procedure turn execution, and missed approach procedures.
(c). Minimums section. The minimums section will provide a minimum descent altitude (based on speed 1.3 * VSo) given the avionics available or circling procedure. (On an ILS approach, localizer only will demand higher mins, as too will circling).

2. Under certain conditions, pilots may request (or be assigned) visual approaches. That is, if the following are met:
(a). VIZ 3 miles at the surface. 500ft ceiling above min vectoring alt.
(b). Pilot has a visual tally on airport (or aircraft he is following).
(c). Pilot remains in VMC.

3. Closely related to the visual approach is the contact approach. (Digressing here a little...reading the NTSB report and CVR recordings of the BIZ jet that crashed in Aspen a couple years ago, there is discussion among the crew of executing a contact approach). The pilot requests this (it is not assigned by ATC).
(a). Aircraft clear of clouds.
(b). 1 mile viz
(c). Pilot can reasonably continue in present conditions to airport safely.
(d). Controllers may grant approval to contact approach if the reported viz is 1 mile, airport has an IAP/JEPP, and aircraft separation is maintained.

4. Precision Approach Radars (near and dear to my heart) allow controllers to give verbal glide path, azimuth, and range information to pilots. Basically a PAR will give headings, when to commence descent to MDA, aircraft's position each mile from the runway and arrival at missed approach point.

5. When executing a missed approach, the pilot flies to the missed approach point (at or above MDA or DH). If the pilot loses visual reference while circling to land, the turn is continued until established on the missed approach course.














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