LNAV stands for Lateral Navigation, and MDA as you now know, stands for Minimum Descent Altitude. Looking at the example below, the RNAV (GPS) RWY 34 at Newport Municipal, you'll see that under the minimums section there the words 'LNAV MDA' are written. Under the minimums, you will see different lines of minimums you can fly (this will depend on the type of equipment you have onboard) and whether they correspond to a Decision Altitude or a Minimum Descent Altitude. To find MDA or DA, you'll look to the Minimums section toward the bottom of the chart. Now that you know the theory behind MDAs and DAs let's identify them on approach charts. But if the weather is at minimums, it's entirely likely that you'll be making your continue/go-around decision at DA. In practical terms, you typically descend out of the clouds and have good enough visibility to see your landing runway well before you reach DA. This assures that the obstacle will be in the LPV visual segment to be avoided and that if a missed approach is required, the obstacle will be avoided on the miss which allows for an additional sink value below the DA.īottom line, two TERPS specifications, two answers.Here's how it works: as you descend down the electronic glideslope of an approach, as you reach DA, you look up, determine if you have the three requirements to land, and then make your decision, which is either 1) continue your descent down the glidepath and land, or 2) go missed and start climbing. When an obstacle penetrates the LPV surface, the height of the obstacle is projected back along and up the obstacle surface until it reaches the height of the obstacle on the surface. That makes obstacles that are very close into the runway can penetrate the LPV obstacle surface, but not the LNAV/VNAV level surface. When the sloped obstacle surface reaches a certain distance from the runway, it levels off for a level segment for the balance of the distance. The LNAV/VNAV has a sloped segment and a level segment that are evaluated along the final approach course. The LPV TERPS evaluates a sloped surface that is a straight line in space, all the way to the runway. Regardless, anytime you have two ways of evaluating a GS, each with its own TERPS obstacle clearance requirements, there are bound to be cases such as the Raleigh one. The WAAS usage of the LNAV/VNAV is based on certain limitations in the vertical path GS indications that the WAAS system generates, allowing them to be close enough to the path for the LNAV/VNAV. The LPV is a straight line in space whereas the LNAV/VNAV is a curved path (following the curvature of the earth) and designed for avionics that have a barometric altimeter input that measures MSL height along the curvature of the earth. LNAV/VNAV LPV APV-Baro APV-SBAS (SBAS supported Localiser Performance with vertical guidance) 7 Airspace Concept Workshop 13 Conventional NPA 36 18 LATERAL VERTICAL LOC LOC/DME VOR VOR/DME NDB NDB/DME Description System Performance. The advantage of IAN is that the instrumentation and procedures are very similar to ILS (Cat I), which is the most common approach type flown for most airline pilots. The LNAV/VNAV procedure and LPV procedures are base on different criteria to evaluate obstacle clearance. 1 Answer Sorted by: 6 A Non Precision Approach (NPA) flown with Integrated Approach Navigation (IAN) is not more precise than the same approach flown with LNAV/VNAV.

And the corrections required for very cold temperature are inputted from a table in a similar way. I would imagine that even in a small airplane the altimeter that provides altitude information to the ‘Baro’ GPS is a separate altimeter from the altimeter in the panel of the airplane and has to be adjusted by the pilot as the panel altimeter.Are all the ‘non WAAS’ Garmin 430 ‘Baro’ equipped?.Why a pilot of a WAAS GPS equipped airplane would choose to fly an LNAV/VNAV approach instead of an LPV approach? Are there perhaps airports that have LNAV/VNAV approaches, but don’t have LPV approaches? If that is the case, what is the reason for not having LPV approaches, considering that ground equipment is not necessary for both types of approaches?.There is also an RNP AR APCH navigation specification which covers a different type of approach. I understand that approaches with LNAV/VNAV minimums may be flown by two types of systems, one is a TSO C145A/146A WAAS GPS and the other is a Baro VNAV system.Ĭould somebody kindly answer the following questions: approaches to all 4 minima (LNAV, LP, LNAV/VNAV and LPV). Asked by: Charles22 3106 views baro, IFR, LNAV, LPV, VNAV

Lnav vnav vs lpv