A330 Aircraft Systems Weather Radar PDF

AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL GENERAL Ident.: AS-WXR-00019333.0001001 / 20 MAR 17 Applicable to: ALL This FCTM chapter...

AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL GENERAL Ident.: AS-WXR-00019333.0001001 / 20 MAR 17 Applicable to: ALL This FCTM chapter provides basic knowledge on the use of onboard weather radars. To get all the information on the characteristics, limitations and operational recommendations of each radar, refer to the user guide of the radar manufacturer. Weather detection is based on the reflectivity of water droplets. The weather echo appears on the ND with a color scale that goes from red (high reflectivity) to green (low reflectivity). The intensity of the weather echo is associated with the droplet size, composition and quantity (e.g. the reflectivity of a water particle is five times more than an ice particle of the same size). The flight crew must be aware that the weather radar does not detect weather that has small droplets (e.g. clouds or fog), or that does not have droplets (e.g. clear air turbulence). Weather Radar Principle The purpose of the weather radar is to help the flight crew detect and avoid storm cells (e.g. cumulonimbus). Due to its large vertical expansion, a storm cell does not have the same reflectivity depending on the altitude. The quantity of liquid water in the atmosphere decreases with the altitude. Therefore the reflectivity of a storm cell decreases with the altitude. The upper detection limit of the weather radar is called the radar top. The flight crew must be aware of both of the following: ‐ The radar top is not the visible top of the storm cell ‐ The storm cell and associated turbulence extend significantly above the radar top. ALK A330 FLEET AS-WXR P 1/16 FCTM A→ 15 FEB 23  AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL Reflective Image of a Cumulonimbus WEATHER DETECTION Ident.: AS-WXR-00019334.0001001 / 03 NOV 22 Applicable to: ALL The flight crew uses the following controls and functions to operate the weather radar: ‐ TILT ‐ GAIN ‐ RANGE. MANUAL TILT MANAGEMENT The tilt refers to the angle between the antenna beam centerline and the horizon. The radar uses data from the IRS to stabilize its antenna. Therefore, the antenna tilt is independent of the aircraft pitch and bank angle. Tilt Angle Definition ALK A330 FLEET AS-WXR P 2/16 FCTM ← A to B → 15 FEB 23  AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL The flight crew should regularly scan the area ahead of the aircraft, at several ND ranges. In order to identify the strongest weather returns, the flight crew should tilt the weather radar antenna up and down. To obtain a correct display of a storm cell, the flight crew must use the tilt knob to point the weather radar beam to the most reflective part of the storm cell. A correct tilt setting prevents the overscanning of the storm cell. Note: Common practice is to ensure that the ground return is at the top of the ND screen. Correct Storm Display At high altitude, a storm cell may contain ice particles that have low reflectivity. If the tilt setting is not correct, the ND may display only the upper (less reflective) part of a storm cell (overscanning). As a result, the flight crew may underestimate or not detect a storm cell. Overscanning 1 GAIN SETTING FOR WEATHER DETECTION The flight crew should use the calibrated gain (CAL or AUTO) for weather detection as default mode for the weather radar. The use of the calibrated gain ensures a standard display of the colors on the ND. The flight crew can manually tune the gain to analyze storm cells. Refer to AS-WXR Analysis of Weather Radar Data. ALK A330 FLEET AS-WXR P 3/16 FCTM ←B→ 15 FEB 23  AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL RANGE MANAGEMENT The flight crew should monitor both the long-distance and short-distance weather, in order to be able to efficiently plan appropriate course changes, and to avoid the “blind alley effect”. Refer to AS-WXR Analysis of Weather Radar Data. At long distance ahead of the aircraft, the accuracy of the weather displayed is low, due to both of the following: ‐ The increase in the width of the weather radar beam ‐ Signal attenuation. Therefore, the accuracy of the weather displayed is better for short-distance weather. Accuracy of the Weather Display 2 USE OF THE WEATHER RADAR IN ACCORDANCE WITH THE FLIGHT PHASE Manual Tilt Manual Weather Radars (or Automatic Weather Radars in Manual Tilt Mode) Flight Phase Tilt Setting Comments Manually and gradually tilt up to scan weather TAXI / TAKEOFF (maximum 15 ° up). Then set tilt to 4 ° up. Check the departure path. Adjust the ND range as required and decrease the tilt Compensation of the altitude increase CLIMB angle as the aircraft climbs. to avoid overscanning. 1. Adjust ND range as required In cruise, the combination of the 2. Regularly modify the tilt to scan the weather ahead following ND ranges provides good of the aircraft weather awareness(1): LEVEL 3. When the weather scan is completed, adjust the tilt ‐ 160 NM on the PM ND FLIGHT/CRUISE so that the ground returns appear on the top of the ‐ 80 NM on the PF ND. ND (2) (3). Use shorter ND ranges to track/avoid short-distance weather. Continued on the following page ALK A330 FLEET AS-WXR P 4/16 FCTM ←B→ 15 FEB 23  AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL Continued from the previous page Manual Weather Radars (or Automatic Weather Radars in Manual Tilt Mode) Flight Phase Tilt Setting Comments During descent, adjust the tilt to maintain the ground DESCENT returns on the top of the ND. - Set the tilt to 4 ° up. This tilt setting (4 ° up) prevents the APPROACH display of too many ground returns. (1) For aircraft equipped with a manual weather radar that has only one tilt control knob, use an average tilt value to suit both ND ranges. (2) It is difficult to identify the difference between weather returns and ground returns: A change in the tilt setting causes the shape and color of ground returns to rapidly change. These ground returns eventually disappear. This is not the case for weather returns. (3) For flights above the water, there are no ground returns. Therefore, the flight crew can use any of the following tilt settings at cruise altitude as an initial value before adjustment: ‐ Approximately -6 ° for an ND range of 40 NM, or ‐ Approximately -2 ° for an ND range of 80 NM, or ‐ Approximately -1 ° for an ND range of 160 NM, or ‐ Approximately -1 ° for an ND range of 320 NM. Automatic Tilt Control  Automatic Weather Radars Flight Phase Tilt Setting Comments Manually and gradually tilt up to scan weather TAXI / TAKEOFF (maximum 15 ° up). Then set tilt to AUTO. Check the departure path. Adjust ND range as required. In cruise, the combination of the Set tilt to AUTO. following ND ranges provides good Use manual tilt for storm cell analysis, then set tilt back weather awareness: to AUTO. IN FLIGHT Regularly perform manual scans to enhance weather ‐ 160 NM on the PM ND ‐ 80 NM on the PF ND. awareness, then set tilt back to AUTO. Use shorter ND ranges to track/avoid short-distance weather. ALK A330 FLEET AS-WXR P 5/16 FCTM ←B 15 FEB 23  AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL ANALYSIS OF WEATHER RADAR DATA Applicable to: ALL Ident.: AS-WXR-WXR-00019335.0001001 / 20 MAR 17 ASSESSMENT OF THE VERTICAL EXPANSION OF A STORM CELL The assessment of the vertical expansion of a detected storm cell enables the flight crew to assess the convective energy of the storm cell and therefore to identify its potential threat. Note: The flight crew can increase the gain in order to obtain a more visible display of the top of the storm cell (that contains less reflective ice particles). When flying towards a cell, the flight crew can estimate the vertical expansion of the cloud above/below the aircraft altitude with the following formula: h(ft) is the difference between the radar top altitude and the aircraft altitude. d(NM) is the distance between the aircraft and the storm cell. Tilt(°) is the tilt setting for which the storm cell image disappears from the ND. Example: a weather return that disappears from the ND at 40 NM with a tilt setting of 1 ° down, indicates that the top of the storm cell is 4 000 ft below the aircraft altitude. Assessment of the Vertical Expansion of a Storm Cell Ident.: AS-WXR-WXR-00019336.0001001 / 20 MAR 17 INTERPRETATION OF THE COLORS OF THE WEATHER DISPLAYED ON THE ND Particle reflectivity of a storm cell is independent of the potential weather hazard in the storm cell. There can be a high percentage of humidity in the atmosphere, when near the sea. In this case, thermal convection will produce clouds that are full of water. These clouds will have a high reflectivity, but may not necessarily be a high threat. On the other hand, in equatorial overland regions where specific converging winds produce large-scale uplifts of dry air. As a result, these storm cells have lower reflectivity than mid-latitude ALK A330 FLEET AS-WXR P 6/16 FCTM C→ 15 FEB 23  AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL storm cells, and therefore can be difficult to detect. However turbulence in, or above these clouds may have a higher intensity than indicated by the image on the weather radar display. The flight crew must not underestimate a storm cell with a high vertical expansion, even if the weather return is low. SPECIFIC WEATHER SHAPES The flight crew should carefully observe shapes, more than colors, in order to detect adverse weather conditions. Areas of different colors that are near to one another usually indicate zones of severe turbulence. Some shapes are good indicators of severe hail and signify strong vertical drafts. Shapes that change quickly, whatever form they take, also indicate high weather activity. Specific Weather Shapes BLIND ALLEY EFFECT The flight crew should determine appropriate course changes to avoid adverse weather conditions, with the use of both high and short ND ranges. This technique avoids the “blind alley effect", defined by the following: a course change that may appear safe with a short ND range, may be blocked when observed with a higher ND range. ALK A330 FLEET AS-WXR P 7/16 FCTM ←C→ 15 FEB 23  AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL Blind Alley Effect ATTENUATION EFFECT In areas of heavy precipitation, an important part of the weather radar signal is reflected by the frontal part of the precipitation due to its strong reflectivity. Therefore, the area behind the precipitation returns low signals, that appears as green or black areas (storm shadows). Attenuation of long-distance weather or attenuation of ground returns can help the flight crew to identify an area of heavy precipitation that may be a very active storm cell. Some radars provide an indication on the ND to highlight areas that may be affected by attenuation: ‐ PAC alert on Collins radars  Refer to FCOM/DSC-34-20-30-30 Weather Radar indication on ND ‐ REACT function on Honeywell radars  Refer to FCOM/DSC-34-20-30-30 Weather Hazard Prediction Function Indication on ND. Note: On a weather radar display, the flight crew should always consider a black hole behind a red area as a potentially very active zone. ALK A330 FLEET AS-WXR P 8/16 FCTM ←C→ 15 FEB 23  AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL Use of Attenuation Effect to Identify an Active Storm Cell USE OF MANUAL GAIN FOR WEATHER ANALYSIS To assess the general weather conditions, the flight crew can use manual gain. Manual gain adjusts the color calibration of the radar. Therefore, the weather will appear either stronger (gain increased) or weaker (gain reduced). When operating in heavy rain, the weather radar picture can be saturated. In this case, manually reduce the gain will help the flight crew to identify the areas of heaviest rainfall, that are usually associated with active storm cells. Note: After a storm cell analysis, the flight crew must set the GAIN knob back to AUTO/CAL. Use of Reduced Gain to Identify Heaviest Rainfall RADAR INTERFERENCE High power external radio frequency sources that operate at a frequency next to the frequency of the weather radar may create interferences. These interferences may result in a not usual return ALK A330 FLEET AS-WXR P 9/16 FCTM ←C→ 15 FEB 23  AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL display on the ND. The radar return will appear as a single wedge that extends out along the ND toward the source of interference. The width and color of the interference may differ on the ND, depending on the distance to the source and its strength. This interference does not damage the radar system, and will disappear as soon as the source of interference is outside the limit of the radar scan zone. Note: Radar interference may also be known as ‘spoking’ or ‘alien radar’. Radar Interference OPERATIONS IN CONVECTIVE WEATHER Ident.: AS-WXR-00019337.0001001 / 26 NOV 19 Applicable to: ALL The flight crew should apply the following operational recommendations in convective weather conditions. These recommendations are applicable in addition to basic knowledge of meteorology and of operation in adverse weather conditions. ALK A330 FLEET AS-WXR P 10/16 FCTM ← C to D → 15 FEB 23  AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL Weather detection: ‐ Always consider that a convective cloud may be dangerous, even if the weather echo is weak. Remember that the weather radar detects only water droplets ‐ Frequent lightning may indicate an area with high probability of severe turbulence ‐ Remember that the TURB function detects areas of wet turbulence only Avoidance decision: ‐ Establish an "area of greatest threat" based on the locations and shape of the strongest weather radar echoes, and on the meteorological knowledge of the flight crew. This "area of greatest threat" corresponds to the zone where the flight crew estimates that the weather conditions are too dangerous to fly in ‐ The weather hazard prediction function (if installed) indicates zones with a high probability of weather hazards (hail or lightning). Avoidance of the detected weather always has priority over avoidance of the weather hazards. As a priority, apply the recommendations to avoid storms, and avoid hazard areas as much as possible ‐ Initiate your avoidance maneuver as early as possible. As the aircraft gets nearer to the convective weather zone, the information from the weather radar often becomes partial. Consider a minimum distance of 40 NM from the convective cloud to make the decision for avoidance maneuver. Avoidance technique: ‐ If possible, perform lateral avoidance instead of vertical avoidance. Vertical avoidance is in general not recommended, particularly at high altitude, due to the reduction of buffet and performance margins. In addition, some convective clouds may have a significant and unpredictable build-up speed. ‐ Lateral avoidance: If possible, deviate upwind instead of downwind. Usually, there is less turbulence and hail upwind of a convective cloud If possible, avoid the identified “area of greatest threat" by at least 20 NM Apply an additional margin if the convective clouds are very dynamic ‐ Vertical avoidance: Avoid flying below a convective cloud, even in visual conditions, due to possible severe turbulence, windshear, microbursts, lightning strikes and hail. If an aircraft must fly below a convective cloud, the flight crew should take into account all indications (visual judgement, weather radar, weather report, pilot’s report, etc.) before they take the final decision For flight above a convective cloud, apply a vertical margin of 5 000 ft from the identified “area of greatest threat". ALK A330 FLEET AS-WXR P 11/16 FCTM ←D→ 15 FEB 23  AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL ICE CRYSTALS Ident.: AS-WXR-00020895.0001001 / 06 JUL 17 Applicable to: ALL GENERAL Clouds are made of particles of water that can be either liquid or solid. Ice crystals are very small solid water particles. In some areas, there may be a very high concentration of ice crystals that may have adverse effect on the aircraft. Areas of ice crystals are usually next to, or above the core of convective clouds that have high-intensity precipitation. However, areas of ice crystals may sometimes even be several nautical miles away from the core of the associated convective cloud. When ice crystals get in contact with a hot surface, they melt. Depending on the type of surface, a water film may appear. On the windshield, this water film creates not-expected appearance of “rain" at temperatures too low for liquid water to exist. If there is a specific airflow towards a zone of the aircraft where water can build up, accretion may occur and create a block of ice. This is why flight in areas of ice crystals may result in various effects, for example engine vibrations, engine power loss, engine damage, or icing of air data probes. ALK A330 FLEET AS-WXR P 12/16 FCTM ← D to E → 15 FEB 23  AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL DETECTION OF ICE CRYSTALS Ice crystals are difficult to detect with the weather radar, because their reflectivity is very low due to both their small size and solid state. In addition, in areas of ice crystals, the flight crew should not expect significant icing of the airframe. This is because ice crystals bounce off cold aircraft surfaces. This is why even the ice detection system does not detect ice crystals, because ice crystals do not build up on ice detectors and visual ice indicators. However, areas of ice crystals are usually associated with visible moisture. Ice crystals can be indicated by one or more of the following: ‐ Appearance of rain on the windshield at temperatures too low for rain to exist. This “rain" is usually associated with a “Shhhh" noise ‐ Small accumulation of ice particles on wipers ‐ Smell of ozone or Saint Elmo’s fire ‐ Aircraft TAT indication that remains near 0 °C (due to freezing of the TAT probe) ‐ Light to moderate turbulence in IMC at high altitude ‐ No significant radar echo at high aircraft altitude, combined with: High-intensity precipitation that appears below the aircraft, or Aircraft position downwind of a very active convective cloud. Isolated Continental Thunderstorm ALK A330 FLEET AS-WXR P 13/16 FCTM ←E→ 15 FEB 23  AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL Mesoscale Convective Cloud OPERATIONAL RECOMMENDATIONS FOR ICE CRYSTALS If possible, the flight crew should avoid flight into areas that have a high concentration of ice crystals. The following recommendations apply: ‐ Use the weather radar: Identify areas that have a strong echo, and perform a detailed analysis of the structure of the convective clouds If necessary, use the weather radar manual modes for a more precise analysis Pay particular attention to strong echoes below the aircraft and to downwind areas. ‐ To avoid convective clouds, comply with operational recommendations (Refer to AS-WXR Operations in Convective Weather), particularly: Prefer lateral to vertical avoidance Comply with the avoidance margins Deviate upwind instead of downwind. ALK A330 FLEET AS-WXR P 14/16 FCTM ←E→ 15 FEB 23  AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL If the aircraft encounters ice crystals precipitation despite avoidance action, and if this results in engines or probes misbehaviors, the published procedures and recommendations apply, and in particular: ‐ ECAM alerts related to engine failure or engine stall ‐ ECAM alerts related to probe failure ‐ QRH procedures such as the ones linked to unreliable airspeed indication, engine vibrations, engine relight in flight… ALK A330 FLEET AS-WXR P 15/16 FCTM ←E 15 FEB 23  AIRCRAFT SYSTEMS WEATHER RADAR A330 FLIGHT CREW TECHNIQUES MANUAL Intentionally left blank ALK A330 FLEET AS-WXR P 16/16 FCTM 15 FEB 23