Low Altitude Alert While on GS

Murdoughnut

Well sized member
A few days ago I was on the glideslope for the ILS 35R at St. Pete/Clearwater. I had just broken out when the tower called me to see if I had the airport in sight because he was getting a low altitude alert message.

Is that normal to get a low altitude alert for an aircraft on the glideslope? Just making sure my equipment isn't FUBAR.

Thanks
 

fish314

Well-Known Member
The back course approach doesn't have a glideslope, but assuming you were above any MDA's or step-downs, then it's kind of the same I guess.

I had one on a non-precision approach once (VOR something or other to someplace or other--don't remember exactly). Anyhow, the controller advised me that I had set off a low-altitude alert and I put the airplane like 20 degrees nose high, maxed the power and tried to re-swallow my heart.

He then told me that they always get that alert with that particular approach... So I concluded that it wasn't really the big deal that I thought it was... and I hadn't actually descended below something on the approach plate.

I then changed my shorts.
 

MikeFavinger

Hubschrauber Flieger
There was a good topic about this a while back, but no idea where it is.

I had a long converstation with the controller at HFD about this because I would always set off the low altitude alert on the LDA 2. (First couple times it happened in the soup my reaction matched Fish's!) Essentially, because I was usually slam dunked into HFD, I had to lose altitude quickly on the approach in order to get stabilized when I supposed to. The computers saw the rapid altitude loss and predicted I would eventually be too low at some point on the approach, even though I was currently above the MDA. The predictive software, said the controller, was pretty sensitive.

On a glideslope though... that explanation doesn't fit, so no idea.
 

KC Jake

Well-Known Member
The back course approach doesn't have a glideslope, but assuming you were above any MDA's or step-downs, then it's kind of the same I guess.

I had one on a non-precision approach once (VOR something or other to someplace or other--don't remember exactly). Anyhow, the controller advised me that I had set off a low-altitude alert and I put the airplane like 20 degrees nose high, maxed the power and tried to re-swallow my heart.

He then told me that they always get that alert with that particular approach... So I concluded that it wasn't really the big deal that I thought it was... and I hadn't actually descended below something on the approach plate.

I then changed my shorts.
The VOR A IXD in Kansas City will get you a low altitude alert every time. Even if you're 100 feet above MDA.
 

matt152

Well-Known Member
The computers saw the rapid altitude loss and predicted I would eventually be too low at some point on the approach, even though I was currently above the MDA. The predictive software, said the controller, was pretty sensitive.
Yes, this is exactly how it works. I set off the "low altitude alert" three times today on each of three VOR 2 approaches at BAF. I was never below the MDA, but was descending at about 700 fpm prior to leveling off.
 

whysoserial

New Member
I don't know the exact details and parameters of it but the LA is based on descent rate. If it detects it, we will get an alarm. Depending on certain things, we will issue you the alert. Example: If you are on a visual approach and we see you and all looks fine, we will not issue it. If on an approach, you will be informed. If you are VFR, the LA will be disabled for you so don't expect it :)
 

scooter2525

Very well Member
There was a good topic about this a while back, but no idea where it is.

I had a long converstation with the controller at HFD about this because I would always set off the low altitude alert on the LDA 2. (First couple times it happened in the soup my reaction matched Fish's!) Essentially, because I was usually slam dunked into HFD, I had to lose altitude quickly on the approach in order to get stabilized when I supposed to. The computers saw the rapid altitude loss and predicted I would eventually be too low at some point on the approach, even though I was currently above the MDA. The predictive software, said the controller, was pretty sensitive.

On a glideslope though... that explanation doesn't fit, so no idea.
I had the same thing going into HFD. I was cleared visual and it was still twilight, so I knew I wasn't about to hit anything. They gave me the current altimeter and I just preceded to the airport. TEB had the same issues....
 

Propilot

Well-Known Member
Yea, I have had that happen a few times in KISP and in Montreal.

After the third time, I asked for a number to get to the bottom of it. I got the "descent rate" explanation.


Kinda bad, because once I knew that it didn't mean much to me other than recheck location/alt.
 

KLB

Well-Known Member
I've gotten that alert from controllers on non precision approaches quite a few times....especially off of the VOR approach for one of the runway 9's into OAK. It spooked me the first couple of times because it had me thinking that I accidentally decended below until a controller explained to me one day that it was due to a high rate a decent.
 

KLB

Well-Known Member
All the time in Montgomery in San Diego. Never got an explanation.
Oh yeah. I remember getting it there all the time also. It's always scary because you don't cross the hill by much to begin with.:)
 

matt152

Well-Known Member
I nearly got it again yesterday. The alert must have gone off in the tower because the tower controller called "Cessna XXX low alt... er disregard" when he saw we were still 500 above MDA.
 
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