I am sitting at work right now, so i cant really reference anything at the moment. Let me try to explain off the top of my head. Principle operation of DME is that your aircraft sends out an interrogating signal made up of paired pulses at a specific spacing, which are then received by the DME ground antenna. The ground station then responds by sending back a pair of pulses to interrogate the aircraft. The signal sent out by the ground station is at 2700HZ and each aircraft uses 30HZ. So if you do the simple math, that means that only 90 aircraft can use a DME station at once. Thats why they tell air-carriers to turn off their DME when sitting at the gate.
missed oral exam questions
- Thread starter SJFLYER
- Start date
E_Dawg
Moderator
#1) Two classes: I - regular NOTAMS (recieved via a preflight briefing), and II - published NOTAMS
- it's a lame question but it was asked on my instrument oral
#2) http://www.aopa.org/asf/publications/sa09.pdf for complete info; one thing to remember is that many ASOSs are privately owned; AWOSs are exclusively funded by the government.
ASOS D - no human observation
ASOS C - possible human observation (part time)
ASOS B - 24 hrs / day human observation
ASOS A - human observation that includes RVR every 10 minutes
The article is good; I didn't even know there was more than one version of ASOS before I read it.
#4) It's just a hypothetical question, but I was also asked that. The answer is South because it is exempt from the north / south turning errors and any turn that is made will be exaggerated and will show immeaditealy.
- it's a lame question but it was asked on my instrument oral
#2) http://www.aopa.org/asf/publications/sa09.pdf for complete info; one thing to remember is that many ASOSs are privately owned; AWOSs are exclusively funded by the government.
ASOS D - no human observation
ASOS C - possible human observation (part time)
ASOS B - 24 hrs / day human observation
ASOS A - human observation that includes RVR every 10 minutes
The article is good; I didn't even know there was more than one version of ASOS before I read it.
#4) It's just a hypothetical question, but I was also asked that. The answer is South because it is exempt from the north / south turning errors and any turn that is made will be exaggerated and will show immeaditealy.
EatSleepFly
Well-Known Member
Hmm...thats interesting FOD. Makes sense I guess, I've just never heard that. Cool...I learned something new.
Not to sure who your check pilot was, but i would argue that point of turning to south just because of the mag compass errors. Yeah i understand his arguement that turning to a south heading will show a turn in the proper direction, but what if a turn to south keeps you in IMC. I would rather turn to VMC conditions, if you are worried about the errors then just keep a shallow turn less then half standard rate and those erros wont be signifficant. I see no need to avoid certain headings because of certian errors, we practice mag compass turns so that we can fly by the mag compass and take into account these errors, not avoid them.
Yeah, it is a hypothetical question. But back to mag compass turns, there is no need to use your TC during mag compass turns. Perhaps you have mag compass turns mixed up with timed turns. During timed turns you need your TC or AI in order to hold a standard-rate turn. But during mag compass turns you need to know the latitude your at and when to roll-out. Overshoot southern headings and Undershoot northerly headings.
pscraig
Well-Known Member
[ QUOTE ]
. The signal sent out by the ground station is at 2700HZ and each aircraft uses 30HZ. So if you do the simple math, that means that only 90 aircraft can use a DME station at once.
[/ QUOTE ]
Not exactly. Most DME/TACAN ground stations are 252-channel two-band (X&Y) units with a capacity of 100 aircraft, but not for the reason you mention. The system capacity of DME is dependent on the distance of the aircraft using the facility. From my notes, around 12 milliseconds are needed for a complete pulse pair for an aircraft at 30nm from the facility. 1 second=1000 milliseconds, divided by 12=~83 aircraft max at that distance.
. The signal sent out by the ground station is at 2700HZ and each aircraft uses 30HZ. So if you do the simple math, that means that only 90 aircraft can use a DME station at once.
[/ QUOTE ]
Not exactly. Most DME/TACAN ground stations are 252-channel two-band (X&Y) units with a capacity of 100 aircraft, but not for the reason you mention. The system capacity of DME is dependent on the distance of the aircraft using the facility. From my notes, around 12 milliseconds are needed for a complete pulse pair for an aircraft at 30nm from the facility. 1 second=1000 milliseconds, divided by 12=~83 aircraft max at that distance.
Alright, i dug up my old notes to get specifics. The aircraft interogates the ground station by sending out 150 pulse pairs per second. When it receives a reply, it reduces its pulse transmission frequency from 150 puls pairs per second to 30 pulse pairs per second. This is to allow the ground station to handle more aircraft. The standard ground station can transmit 2700 replies per second. With each aircraft sending 30 pulse pair interrogations per second, the total number of aircraft that the ground station can service at once is 90 (2700 repliers per station/ 30 interrogations per aircraft= 90).
Peak interrogation pulse power is about 50 watts. The ground station will not reply to the 91st lowest power interrogations. Thus, if we are 130 NM from a DME ground station, and we are the 90th lowest power interrogations, and an aircraft takes off near the station, we may be bumped and lose our DME.
Peak interrogation pulse power is about 50 watts. The ground station will not reply to the 91st lowest power interrogations. Thus, if we are 130 NM from a DME ground station, and we are the 90th lowest power interrogations, and an aircraft takes off near the station, we may be bumped and lose our DME.
stultus
New Member
Well I just got done with my oral a couple of hours ago...couldn't go on the flight because of the WX.
I had 1 minor problem and 1 punt.
When he asked me to describe the electrical system I got the numbers mixed up and said it was a 12 volt system and a 14 volt battery...he asked me if was sure and that made me know I had gotten something confused, thought about it and came up with the right answer.
The last section of questioning was on aeromedical factors and he asked me about the effects of dehydration (
new to the PTS this year) I didn't have a clue, never talked about it with my instructor and don't remember anything from ground school or my own studies so I told him I didn't know. Everything had gone so well up to that point, I didn't want to look like a fool so I just told him the truch "I don't know." He said "are you sure, the whole exam depends on this one question"...then he laughed and we talked about it a little. Then he asked me about hyperventilation. I hit a home run. Then he commented on what I said... "yeah, hopefully it's not the pilot hyperventilating...it's really important to keep your pax as calm as possible and get them to talk. If you have that bag with, have them use it if you have to...if you have a girl with just make sure not to tell her to put the bag over her head...it's all over at that point, you can't recover from that."
I had 1 minor problem and 1 punt.
When he asked me to describe the electrical system I got the numbers mixed up and said it was a 12 volt system and a 14 volt battery...he asked me if was sure and that made me know I had gotten something confused, thought about it and came up with the right answer.
The last section of questioning was on aeromedical factors and he asked me about the effects of dehydration (
172's are for the most part placarded against slips with flaps. The reason is it can cause ELEVATOR oscillations not rudder. From Cessna "under certain combinations of airspeed and CG loadings the elevator might have a slight tendency to oscillate" That said I've heard of people to try to get the elevator to do this and have not been successful.
johnbail
New Member
[ QUOTE ]
SkyGuy,
Here ponder this one for a while-
1- When filing GPS direct from JFK to LAX, how many waypoints do you need to file?
[/ QUOTE ]
I thought I read in the AIM that youhad to list one raido fix through each control aera you pas through.
from the AIM
c. Direct Flights
1. All or any portions of the route which will not be flown on the radials or courses of established airways or routes, such as direct route flights, must be defined by indicating the radio fixes over which the flight will pass. Fixes selected to define the route shall be those over which the position of the aircraft can be accurately determined. Such fixes automatically become compulsory reporting points for the flight, unless advised otherwise by ATC. Only those navigational aids established for use in a particular structure; i.e., in the low or high structures, may be used to define the en route phase of a direct flight within that altitude structure.
am I right I am still studing for for my IFR written
SkyGuy,
Here ponder this one for a while-
1- When filing GPS direct from JFK to LAX, how many waypoints do you need to file?
[/ QUOTE ]
I thought I read in the AIM that youhad to list one raido fix through each control aera you pas through.
from the AIM
c. Direct Flights
1. All or any portions of the route which will not be flown on the radials or courses of established airways or routes, such as direct route flights, must be defined by indicating the radio fixes over which the flight will pass. Fixes selected to define the route shall be those over which the position of the aircraft can be accurately determined. Such fixes automatically become compulsory reporting points for the flight, unless advised otherwise by ATC. Only those navigational aids established for use in a particular structure; i.e., in the low or high structures, may be used to define the en route phase of a direct flight within that altitude structure.
am I right I am still studing for for my IFR written
RiddlePilot
New Member
Neat topic. I'll relate one I missed on my stage 1 checkride for FA304 here at ERAU (multiengine instrument).
We were referencing the SUNSS5 Arrival, San Simon transition when he pointed to an altitude along the arrival and asked "If ATC says 'Seminole 570ER, cross San Simon at 12,000, cleared for the SUNSS5 arrival,' can you descend via the arrival as published?"
My logical thinking was "yes," but the answer is really "no," as ATC did not issue the magic words of "descend via" the arrival. Oops.
We were referencing the SUNSS5 Arrival, San Simon transition when he pointed to an altitude along the arrival and asked "If ATC says 'Seminole 570ER, cross San Simon at 12,000, cleared for the SUNSS5 arrival,' can you descend via the arrival as published?"
My logical thinking was "yes," but the answer is really "no," as ATC did not issue the magic words of "descend via" the arrival. Oops.
