Question from a non-pilot about IFR ?

Question

What exactly does the pilot rely on to keep course thru clouds or approach in bad weather.

Is it a computer generated "image" of the runway ? Computer commands?

Thanks in advance. It's really cool that you pilots are so eager to share your knowledge with us Land Folk.

Answer 1

There are several systems that are used.

GPS is the newest and is quickly becoming the most common.

Generally with Traffic, Terrain and Weather overlays.

Imagine looking at a GPS screen that shows the hills, highways, add'l traffic and clouds around you - that's what it's like.

Check out Garmin.com and look for Panel Mounts --- this will show you some of the screens that are used.

(https://buy.garmin.com/shop/shop.do?cID=...

Answer 2

the visualiyed szstems for IFR enroute procedures /so - called highway consisting of squares to be flown "through"/ is not widely used. more usuallz the pilot relies on the various szstems like GPS, ILS and others that use some kind of command arrows or bars to show the position of the  plane relative to the source of navigation.

so basically the ILS for instance provides the cross, ADF provides homing on an arrow, and RNAV when used with the VOR provides lateral bar with desired inbound heading selector

the GPS also can be used together with map-imaging, which draws aircraft position over the map layer, to show the exact position together with the map. some use scanned physical maps, others use simplified JEPESSEN airspace vector images.

Answer 3

Under IFR, the primary means of navigation are either via radio beacons on the ground, such as VORs and NDBs, or GPS. In areas of radar coverage, ATC may also assign headings to IFR aircraft, also known as radar vectors. Radar vectors are the primary method for ATC to provide separation between aircraft for landing.

Most important are: Attitude Indicator (artificial horizon) , Airspeed Indicator, VS (Vertical Speed Indicator), Turn Coordinator - An Instrument Pilot also uses VOR/With glide Slope or HSI , DME Information , GPS

In more sphisticated aircraft the autopilot can be coupled to a flight director or navigational aid such as gps etc and the aircraft will fly an approach automatically, provided its programmed correctly.

Here is some more info ,,,,,  

IFR" redirects here. For other uses, see IFR (disambiguation).

Instrument flight rules (IFR) are a set of regulations and procedures for flying aircraft whereby navigation and obstacle clearance is maintained with reference to aircraft instruments only, while separation from other aircraft is provided by Air Traffic Control. In layman's terms, a pilot who is rated for IFR can keep a plane in controlled flight solely on the data provided by his instruments, even if that pilot cannot see anything (useful) out the cockpit windows; indeed, one of the benefits of these regulations are the ability to navigate fly through clouds, which is otherwise not allowed.

IFR is an alternative to visual flight rules (VFR), where the pilot is ultimately responsible for navigation, obstacle clearance and traffic separation using the see-and-avoid concept. The vast majority of commercial traffic (any flight for hire) and all scheduled air carriers operate exclusively under IFR. Commercial aircraft providing sight seeing flights, aerial photography, or lift services for parachute jumping usually operate under VFR.

Separation

This article or section deals primarily with the United States and does not represent a worldwide view of the subject.

Please improve this article or discuss the issue on the talk page.

The distance by which an aircraft avoids obstacles or other aircraft is termed separation. The most important concept of IFR flying is that separation is maintained regardless of meteorological visibility conditions. In controlled airspace, Air Traffic Control (ATC) separates IFR aircraft from obstacles and other IFR and known VFR aircraft by applying a flight clearance based on route, time, distance, speed, and altitude differences between aircraft. ATC monitors IFR flights by relying either on radar or aircraft position reports. Aircraft position reports are traditionally sent as voice radio transmissions, but increasingly also as electronic data exchanges. Aircraft position reports are not necessary if ATC has an aircraft in radar contact. In the United States a flight operating under IFR is required to fall back to position reports if advised radar contact lost.

IFR flights require an ATC clearance for each part of the flight. A clearance always specifies a clearance limit, which is the farthest the aircraft can fly without a new clearance. In addition, a clearance typically provides a heading or route to follow, altitude, and communication parameters, such as frequencies and transponder codes. An aircraft operating VFR must also obtain a clearance to enter class B and class C airspace, and is required to maintain an assigned heading or altitude restriction as long as it does not conflict with the safe operation of the aircraft.

In uncontrolled airspace, IFR aircraft do not require clearances, and they separate themselves from each other by using charted minimum altitudes to avoid terrain and obstacles, standard cruising altitudes to avoid aircraft flying in different directions, and radio reports over mandatory locations.

In the United States and the Southern Domestic Airspace of Canada (SDA), airspace from 18,000 to 60,000 feet (5,586 to 18,288 meters) is designated as class A, requiring an IFR clearance for all aircraft. In other countries class A airspace begins higher or lower. For example, in France class A airspace begins at 19,500 feet (5,850 meters).

In the United States even when on a filed IFR flight plan, if conditions permit the pilot is responsible to maintain a watch for, and avoid other air traffic and obstructions. Separation may also be referred to as 'protection'.

[edit] Weather

One main purpose of IFR is the safe operation of aircraft in Instrument Meteorological Conditions (IMC). The weather is considered to be IMC when it does not meet the minimum requirements for Visual Meteorological Conditions. To operate safely in IMC , a pilot controls the aircraft relying on flight instruments, and ATC provides separation.



VMC Flying under IFR RulesIt is important to not to confuse IFR with IMC. The vast majority of IFR flying is conducted in Visual Meteorological Conditions (VMC). Any time a flight is operating in VMC, the crew is responsible for seeing and avoiding other traffic, however, since the flight is conducted under Instrument Flight Rules, ATC still provides separation services.

During flight under IFR, there are no visibility requirements, and as such flying through clouds is permitted. There are still minimum conditions that must be present in order for the aircraft to take off and land; these will vary according to the type of navigation aids available, the location and height of terrain and obstructions in the vicinity of the airport, equipment on the aircraft, and according to qualifications of the crew. For example, landing at mountain airports such as Reno (KRNO) offer significantly different instrument approaches for aircraft landing on the same runway, but from opposite directions. Aircraft approaching from the north must make visual contact with the airport at a higher altitude than a flight approaching from the south, because of rapidly rising terrain south of the airport. This higher alltitude allows a flight crew to start a climb earlier in case landing is not feasible.

Although large airliners and, increasingly, smaller aircraft now carry their own terrain- and collision-avoidance systems such as TCAS, these are primarily backup systems providing a last layer of defense if a sequence of errors or omissions causes a dangerous situation.

[edit] Navigation

Under IFR, the primary means of navigation are either via radio beacons on the ground, such as VORs and NDBs, or GPS. In areas of radar coverage, ATC may also assign headings to IFR aircraft, also known as radar vectors. Radar vectors are the primary method for ATC to provide separation between aircraft for landing.

Modern Flight Management Systems have evolved sufficiently to allow a crew to plan a flight not only as to route and altitude, but to specific time of arrival at specific locations. This capability is used in several trial projects experimenting with four dimensional approach clearances for commercial aircraft, with time as the fourth dimension. These clearances allow ATC to optimize the arrival of aircraft at major airports, which increases airport capacity, and uses less fuel providing monetary and environmental benefits to airlines and the public at large respectively.

Required Navigation Performance (RNP)

ADS-B

[edit] Procedures

There are three stages to an IFR flight: departure, en route, and approach. For each stage there are standard, published procedures to allow IFR aircraft to move in a safe, orderly way, from the moment the wheels leave the runway to the moment they touch down again. These procedures also allow an IFR aircraft to complete a flight predictably in case of communication failure (lost-comm) with ATC, with default altitudes and headings for every stage. An IFR flight typically starts with an IFR clearance, which specifies the departure instructions, and any modifications to the route. Here is an example of an IFR clearance, for a Cessna aircraft traveling from Palo Alto airport (KPAO) to Stockton airport (KSCK).

"Cessna 6253G is cleared to Stockton Airport. After departure, turn right heading zero-six-zero within one mile of the airport. Radar Vectors San Jose, Victor-334, SUNOL, Victor-195, Manteca, direct. Climb and maintain 3,000 expect 5,000 five minutes after departure. Departure frequency is 121.3, squawk 4263." Note: Not to be used for Real World Navigation

Detailed explanation:

"Cessna 6253G"

Verifies that only this specific aircraft is cleared.

"is cleared to Stockton Airport."

Clearance Limit: the farthest destination the aircraft is allowed to go under IMC (in most cases it is the destination airport).

"After departure, turn right heading zero-six-zero within one mile of the airport."

The Pilot is expected to execute the turn without further ATC prompting.

"Radar Vectors San Jose"

The departure controller will provide directional guidance to the San Jose VOR.

"Victor-334, SUNOL, Victor-195, Manteca, direct."

After arriving at the San Jose VOR, the pilot will likely resume navigation without ATC prompts along the described airways and intersection to the Manteca VOR and then direct to the destination airport.

"Climb and maintain 3,000 ..."

After takeoff, climb to an altitude of 3000 feet above sea level.

"... expect 5,000 five minutes after departure."

Your final altitude assignment is probably going to be 5000 feet above sea level. However, you must follow actual ATC altitude assignments throughout the flight. This portion of the clearance provides a backup if communications are lost, allowing you to proceed to climb and maintain 5000 feet.

"Departure frequency is 121.3, ..."

Contact with NORCAL Departure on the specified communication frequency, after Palo Alto Tower tells you to switch.

"... squawk 4263.

Answer 4

GPS is definitely the most modern method of guidance for most aircraft. You can still navigate by VOR's and I guess there are still a few NDB's around (both are ground based radio navigation aids).

I'll just add that there are some interesting new things coming out also that add new levels of situational awareness in bad weather.

There are some computer systems coming out now that do actually present a computer generated image of runways and so forth. I don't know if any are actually certified for IFR flight or not yet.

Also, a lot of newer high end aircraft are being equipped with infrared video imaging systems on stand alone monitors or drop downs for the wind screens. These can actually allow a pilot to see a runway or things on the ramp in zero visibility. Whether any of these systems are yet certified for anything more than enhanced SA, I don't know.

All IFR approaches have what are known as "minimums;" the lowest level of cloud obscuration and horizontal visibility you are allowed to have so you can actually have visual contact with the runway before you have to abort the landing and try again or head to an alternate. The minimums will vary depending on the type of approach and how well equipped the aircraft is (has the certified equipment on board capable of safe guidance to the minima specified for that approach).