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Sink Rate "Dont Sink"  
User currently offlineDavid B. From United States of America, joined Jun 2001, 3148 posts, RR: 5
Posted (12 years 5 months 2 weeks 2 days 9 hours ago) and read 20673 times:

What is a sink rate of a aircraft? And what does it mean when the GPWS tells you "Dont Sink"?


Teenage-know-it-alls should be shot on sight
42 replies: All unread, showing first 25:
 
User currently offlineSxmarbury33 From United States of America, joined Oct 2000, 445 posts, RR: 0
Reply 1, posted (12 years 5 months 2 weeks 2 days 9 hours ago) and read 20750 times:

The GPWS callout sink rate is when the aircraft is approaching the ground faster than it should be in normal service. This is probably the most frequent alert because its just a matter of a few hundred feet persecond. If this is not corrected you may get the terrian and or pull up warning. The dont sink warning is mainly for after takeoff. If the GPWS senses from the RA that the aircraft is decending after the takeoff it will give an aural call out to warn the pilot.

User currently offlineWilcharl From United States of America, joined Jun 2000, 1168 posts, RR: 3
Reply 2, posted (12 years 5 months 2 weeks 2 days 9 hours ago) and read 20697 times:

Thats on all airlines except NW, on NW they have an STC that allows them to modify their GPWS to say "Don't Drink... Don't Drink"

User currently offlineAvt007 From Canada, joined Jul 2000, 2132 posts, RR: 5
Reply 3, posted (12 years 5 months 2 weeks 2 days 8 hours ago) and read 20662 times:

And here I always thought it said "don't think"!

User currently offline777236ER From , joined Dec 1969, posts, RR:
Reply 4, posted (12 years 5 months 2 weeks 2 days 8 hours ago) and read 20671 times:

"Don't sink" is after take off to ensure that they keep on climbing immediately after take off. "Sink rate" is at any other time when the sink rate gets excessive.

User currently offlinePPGMD From United States of America, joined Sep 2001, 2453 posts, RR: 0
Reply 5, posted (12 years 5 months 2 weeks 2 days 8 hours ago) and read 20658 times:

"Sink rate...Sink Rate... Gear... Gea..." Shut up!  Smile

I flew an aircraft with one of those it only lasted about ten mintues before I turned it off, too much of a distraction.



At worst, you screw up and die.
User currently offlineXFSUgimpLB41X From United States of America, joined Aug 2000, 4218 posts, RR: 37
Reply 6, posted (12 years 5 months 2 weeks 2 days 7 hours ago) and read 20647 times:

To further clarify what has been said.. sink rate has to do with the vertical speed of the aircraft. It's easy to get this in a windshear situation after departure or on arrival- the Don't Sink warning comes in when your sink rate has a projected danger of sending you dancing with a hill. I've only heard on departure on a 2 engine failure the DC-10... the most ive heard it is adjusting when coming off of a non-precision approach or visual approach and trying to get the airplane set up for a stabilized final descent. When i first heard the warning, i also thought it said Don't Think.


Chicks dig winglets.
User currently offlineAirplay From , joined Dec 1969, posts, RR:
Reply 7, posted (12 years 5 months 2 weeks 2 days 7 hours ago) and read 20644 times:

There are 5 basic GPWS modes. They are shown below with the associated callouts:

Mode 1 - Excessive Descent Rate (Sink Rate, Pull Up)
Mode 2 - Excessive Terrain Closure Rate (Terrain-Terrain, Pull Up)
Mode 3 - Altitude Loss After Take-off (Don't Sink)
Mode 4 - Unsafe Terrain Clearance (Too Low Gear, Too Low Flaps, Too Low Terrain)
Mode 5 - Excessive Deviation Below Glideslope (Glideslope)

All of these modes have specific aural warnings associated with them which are issued based on specific aircraft performance parameters.

The "SINK RATE" callout is associated with Mode 1 only and is issued when the GPWS detects excessive descent rate for the altitude above ground. It is followed by "PULL UP" at a pre-determined point.

The "DON'T SINK" callout is associated with Mode 3 only and is issued when the aircraft sinks after takeoff. The altitude loss at which the callout is issued is dependant on the height above ground. This mode is inactive above 1500 feet.

These callouts are ONLY used for these instances.



User currently offlineMD11Nut From , joined Dec 1969, posts, RR:
Reply 8, posted (12 years 5 months 2 weeks 2 days 3 hours ago) and read 20588 times:

Someone here seems to take the attitude that these cautions and warnings are nothing but nuisance...I wish you wouldn't take it too slightly.

Perhaps with the exception of Mode 3, "Don't Sink" and occasionally some nuisance alerts, any of the GPWS warnings could literally mean you are seconds from being a grease spot on some hills. I wouldn't turn it off if I were you.

I was on about half a dozen of GPWS flight tests and my impression was that these warnings were darn hard to get. When we get them I'd still remember the chills that ran down my spine, thankful that we were inducing these warnings on purpose. As I recalled, to get Mode 1 "Sink Rate" and the subsequent "Whoop Whoop Pull Up", we had to start out at 2500ft AGL diving straight at the ground at about 3000fpm. It's normal to pull 2.5g in the pull up maneuver. Quite an exciting ride in retrospect. Unless you fly a Dash 8 doing 6 degree path descents at high altitude with high ground speed, if you hear this in real life, better arrest that rate quick. You'd get less than a minute to live, usually.

To test Mode 2, we aimed at a mountain, flying about 200 ft above the top. Because it's Radar Altimeter based, you'd get the "Terrain Terrain" about 15 seconds before impact, the "Whoop Whoop Pull Up" about 10 seconds before impact (if you happen to fly below the peak). You hear this, you immediately aim for the moon. The Cali, Columbia accident in 1995...the airplane got the warning 12 seconds before it hit the mountain. Yes, that was a Mode 2. The Enhanced GPWS (TAWS) would give you about 60 seconds caution (Terrain) and 30 seconds (PULLUP).

Mode 3 was easy to get, takeoff, lose about 80 ft altitude or get a negative climb rate of more than a 100fpm or so then you get it.

To get Mode 4, I remembered you have to be really close to the ground about 500 ft AGL or so before you get "Too Low Terrain", keep getting closer then you get "Too Low Gear" then about 200 ft AGL or so you'd get "Too Low Flaps". We'd pick some flat field out in the desert to do this test. All I would see would be brown earth all around us. I'd hate to run into some high voltage power lines out there.

Mode 5 "Glideslope" wasn't too bad but you have to be a whole dot below glideslope really close to the ground (about 300 ft AGL or so) before you'd get it. I'd react quickly to any of these.

If you are lucky enough that the aircraft you fly has it, use it. Don't turn it off. It could save your life some day. I read somewhere that 70% of all accidents out there are due to one form of CFIT (controlled flight into terrain) or another. A few airliners CFIT accidents happened partly because the crew didn't react to GPWS Pull Up warnings aggressively.

The cheapest GPWS out there is about $8,000 and unfortunately it's not required for part 91 unless the a/c has 6 pax seats or more. So most GA aircraft out there do not have this gem installed. Hopefully it'll get much cheaper really soon.

Best Regards,
Nut


User currently offlineDc10hound From United States of America, joined Dec 2000, 463 posts, RR: 5
Reply 9, posted (12 years 5 months 2 weeks 2 days 2 hours ago) and read 20568 times:



"TERRAIN, TERRAIN"

If there's a train coming, we really are in trouble, are we not?





"Eagles soar. But weasels never get sucked into jet intakes.."
User currently offlinePPGMD From United States of America, joined Sep 2001, 2453 posts, RR: 0
Reply 10, posted (12 years 5 months 2 weeks 1 day 21 hours ago) and read 20539 times:

Well the PC-3 that I have flown on a couple of occasions has an old military one installed in it, way too much of a distraction in a two seat aircraft. It went off constantly while I was in the pattern, maybe the ones in the airliners are a lot better but this one was just plain annoying in a situtation where I had everything under control.


At worst, you screw up and die.
User currently offlineFDXmech From United States of America, joined Mar 2000, 3251 posts, RR: 34
Reply 11, posted (12 years 5 months 2 weeks 1 day 19 hours ago) and read 20523 times:

I view the GPWS as a data consolidater. The GPWS in itself takes data (radio altitude, baro altitude, vertical speed, gear position, flaps, etc) available to the pilots, integrates it, and contructs a picture of potential danger. A valuable system. And now with EGPWS, even better.


You're only as good as your last departure.
User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 12, posted (12 years 5 months 2 weeks 1 day 18 hours ago) and read 20512 times:

Correction:
"It's easy to get this in a windshear situation after departure or on arrival" would trigger an audible "Windshear" warning on a part 121 airliner in an arrival or departure configuration, not "Sink Rate".

Wind Shear warnings have a higher aural priority that GPWS or TCAS.


User currently offlineBio15 From Colombia, joined Mar 2001, 1089 posts, RR: 7
Reply 13, posted (12 years 5 months 2 weeks 1 day 18 hours ago) and read 20505 times:

Interesting post MD11Nut. I dare to correct you though, on the fact that the Cali accident was not in Columbia but COLOMBIA!
-bio


User currently offlineAvt007 From Canada, joined Jul 2000, 2132 posts, RR: 5
Reply 14, posted (12 years 5 months 2 weeks 1 day 14 hours ago) and read 20463 times:

False alarms are a fact of life with gpws. No doubt as newer systems come on line, it will improve, but complacency can be a problem. I worked on gpws snags for 15 years, and false alarms are very common. The biggest problem is everything surrounds the rad alt. The dash8 has lots of snags with these, resulting in terrain warnings in cruise, pull up warnings while taxiing in the rain, too low gear @ 20,000 feet. I can't say as I blame the crews, but hopefully they'll react fast if it's IFR.

User currently offlineAirplay From , joined Dec 1969, posts, RR:
Reply 15, posted (12 years 5 months 2 weeks 1 day 6 hours ago) and read 20415 times:

Essential Power,

With respect to your "correction":

Although windshear detection is a requirement for Part 121 operations, you need to remember that there are other types of operators who do not require it. As a matter of fact a great deal of business aircraft with GPWS or EGPWS/TAWS don't have this option enabled or another form of windshear detection installed. Therefore, in these instances you may in fact get a "SINK RATE" in windshear conditions.



User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 16, posted (12 years 5 months 2 weeks 1 day 6 hours ago) and read 20415 times:

It was readily apparrent that I was referring to part 121 airlines, therefore windshear capable.

Reread it.


User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 17, posted (12 years 5 months 2 weeks 1 day 6 hours ago) and read 20414 times:

Was my statement:

"...would trigger an audible "Windshear" warning on a part 121 airliner in an arrival or departure configuration, not "Sink Rate"."

confusing to you?

He's talking about a DC10 sim at Natco, as his Dad's a -10 capt. My response is accurate as written.

read what was posted.


User currently offlineXFSUgimpLB41X From United States of America, joined Aug 2000, 4218 posts, RR: 37
Reply 18, posted (12 years 5 months 2 weeks 1 day 6 hours ago) and read 20400 times:

I very well could have been confused as to what the GPWS was saying when... I havent had the formal ground school in the 10, just have been taught the SOPA and SMAC and international operations in them... there is a mode check during my preflight flows on the GPWS (which had been upgraded to EGPWS last time i was in there) and i remember it going through all those callouts... just not in that order. When the thing went off i generally was too busy, and just remember it yelling at me about something. I remember a windshear and sink rate callout very close together.... probably was the one on approach from what these modes have been. Also the dont sink one, I suppose that was on the depature windshear, as i have been trained in all the most violent profiles they give the students. The windshear alert always gets called out in the event of one... the other items will follow.




Chicks dig winglets.
User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 19, posted (12 years 5 months 2 weeks 1 day 5 hours ago) and read 20397 times:

I can't really decipher the above para, but it doesn't sound like you're particularly qualified to have answered the topic.

User currently offlineWilcharl From United States of America, joined Jun 2000, 1168 posts, RR: 3
Reply 20, posted (12 years 5 months 2 weeks 1 day 5 hours ago) and read 20393 times:

I think essentialpower thinks that XFSUgimpLB41Xh got his king air "type raiting" (yes i know the king air doesnt require a type raiting, but someone that went there said they had one but anyways... )from Tab aviation in Deadland florida  Smile

User currently offlineXFSUgimpLB41X From United States of America, joined Aug 2000, 4218 posts, RR: 37
Reply 21, posted (12 years 5 months 2 weeks 1 day 5 hours ago) and read 20391 times:

Basically i was agreeing with you, Essential... 121 planes have the windshear mode enabled. Plus i was clarifying that i have not had the groundschool for the DC-10 and the EGPWS...just been through the flight sim portion of training in standard and emergency operating procedures.


I'm typing a 10 page paper and using this site to procrastinate... my responses probably aren't as coherant tonight.



Chicks dig winglets.
User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 22, posted (12 years 5 months 2 weeks 1 day 5 hours ago) and read 20390 times:

No, that's not what EssentialPowr thinks.

User currently offlineEssentialPowr From United States of America, joined Sep 2000, 1820 posts, RR: 2
Reply 23, posted (12 years 5 months 2 weeks 1 day 5 hours ago) and read 20388 times:

XFSU,

No sweat; I call them like I see em. At any rate, I admire your drive, and wish you the best of luck. I'm sure NWA will have an FO seat in the -9 when you're ready.

Cheers-


User currently offlineAirplay From , joined Dec 1969, posts, RR:
Reply 24, posted (12 years 5 months 2 weeks 16 hours ago) and read 20350 times:

More assumptions being made. Not all "airliners" are neccessarily operated part 121. Not all airliners are operated under FAA rules.



25 EssentialPowr : It took you that long to come up with a response after you clearly didn't read the post? That's pathetic. Part 121 ops was implicit, particularly from
26 EssentialPowr : You can call something a "canoe" if you want. As I said, in Part 121 ops, the warning for the situation XFSU described would be: "Windshear". Period.
27 Airplay : In Canada we call it 705. Not 121. And the rules are NOT identical. get it?
28 EssentialPowr : WHo in hell said anything about Canada or similarity of rules? Where is that in this thread? Can you not read??? I said "121". Part 121 means United S
29 EssentialPowr : **For anyone that cares to answer, my first post: "...(XFSU's scenario)....would trigger an audible "Windshear" warning on a part 121 airliner in an a
30 Airplay : You seem to imply that 737's (and other airliners) can not and are not sometimes operated under part 91. You are simply wrong. As far as Part 121 bein
31 Airplay : By the way, in case you don't know, Part 121 covers commercial operators. Check out part 119 for information. It says that commercial operators need t
32 EssentialPowr : BS. Everyone knows some "airliners" are operated part 91; ie Greg Norman's BBJ. I said "121 airliner". Here's the post: Correction: "It's easy to get
33 MD11Nut : I thought Greg Norman negated on getting a BBJ. He said it was too big, too hard to park. I think there's no need to get offended regarding windshear.
34 Airplay : My problem is that you "correct" people who may in fact have stated something correctly. You don't consider alternatives. (Like usual) Then you cry ab
35 EssentialPowr : No. For a Part 121 Airliner in windshear conditions: 1. Windshear warnings have priority over GPWS or TCAS. 2. A/c configuration to enable the Windshe
36 EssentialPowr : I said: "Correction: It's easy to get this in a windshear situation after departure or on arrival" would trigger an audible "Windshear" warning on a p
37 EssentialPowr : My statement "on a part 121 airliner" WAs a correction. Don't dare tell me how to present my topics, or attempt to educate me with your pathetic under
38 Airplay : EP, Your original post stated the word "Correction". That implies that the statement made by XFS contained an error. I am simply pointing out that his
39 Post contains images Ammunition : The funny thing is........ ur all over 25 and possibly in ur mid 30's, professional people and ur arguing like kids..... Reminds of a few non-aviation
40 PPGMD : Arguing with a pilot is like wrestling with a pig in the mud, after a while you begin to think the pig likes it. — Seen on a General Dynamics bullet
41 EssentialPowr : 1. IT did contain an error. XFSU was referring to a DC10 sim at Northwest Airlines, as his dad is a CAptain for them. I recognized this from previous
42 Airplay : EP, You stated: In Canada? No. In a King Air? No. Privately operated Part 91 737? Who knows. These were never part of the topic. I don't recall refere
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