Inside the FMS

The NGFMS Gold package for the Embraer E-Jets (E170/175/190 and 195) adds several airline-specific capabilities to the Basic NGFMS that deliver quantifiable and measurable value to airlines operating these aircraft. NGFMS Gold offers three main benefits to airline operators:

1. Cost Index (CI) and ECON Speeds
2. Wind Trade Steps Evaluation
3. Optimum (Off-Idle) descent path creation and management capability

This article will focus on Wind Trade Steps Evaluation and what crews need to know to take advantage of this feature.

Wind Trade Steps Evaluation uses the NGFMS Atmospheric Model to compare all available flight levels to determine the most cost-efficient (not necessarily fuel-efficient) altitude profile to fly throughout the flight plan based on the Cost Index (CI) value entered by the pilot. It is an enhancement to the Optimized Step Climb functionality that provides guidance to the crew by means of advisory step climb points as to when the aircraft can climb to a more optimum altitude in terms of cost efficiency. This cost efficiency is defined by the CI value and corresponding ECON speeds. The NGFMS uses forecast/uplink winds to ensure the Atmospheric Model is as accurate as possible.

Step increment (STEP INC) is used to specify the amount of airspace that should be considered by the FMS to determine optimum step climb points to a more cost-effective cruise altitude. When a step increment is selected, time and fuel predictions assume that the step climbs are made. Therefore, an optimum step increment must only be selected when the intent is to make the optimum step climbs. When clearance is not given or the optimum step climb is not going to be made, it is very important that the step increment is set to zero in order to maintain accurate time and fuel predictions.

Step Increment Set to Zero

The bottom of step climb (BOSC) information is shown on the CRUISE page of the MCDU.

CRUISE Page

It is also shown on the Multifunction Display (MFD) lateral map and Vertical Situation Display (VSD).

BOSC on the Lateral Map and VSD

During cruise flight, the flight crew will see a vertical track alert (VTA) at one minute prior to the BOSC point. Step climbs use the cruise speed command when the altitude changes are 5,000 feet or less. Climbs greater than 5,000 feet use the climb speed commands.

Through the use of Wind Trade Steps in the Gold package, operators can now sit back, relax, and enjoy the cost savings.